p-block Elements (N & O Family) Exercises

p-block elements (N & O Family)  Marked questions are recommended for Revision. PART - I : SUBJECTIVE QUESTIONS Section (A) : Occurence, Atomic & Physical Properties. A-1. Nitrogen forms a simple diatomic molecule but other elements of same group do not form. Explain. A-2. White phosphorus is very reactive, but not the red one. Why ? A-3. Which allotropic form of sulphur is thermodynamically stable at room temperature and pressure ? A-4. The important source of phosphorus is phosphorite rocks which is mainly phosphates. The same chemical compound is also present in bones. What is the formula of the compound(s). Section (B) : General trends & Chemical Properties. B-1. Why is Bi (V) a stronger oxidant than Sb (V)? B-2. Nitrogen shows different oxidation states in the range ______ to _____. It most stable oxidation state is______ . B-3. The tendency to exhibit –3 oxidation state by a group VA element decreases down the group. Why ? B-4. Why sulphur in vapour state exhibits paramagnetic behaviour at above 800ºC. B-5. Write the following for a white phosphorus molecule : (a) oxidation state of P (b) covalency of P (d) bond order. (e) bond angle (c) total number of bonds (f) geometry B-6. Tellurium forms oxides of the formula TeO, TeO2 and TeO3. What is the nature of these tellurium oxides? B-7. Write the structure and oxidation numbers of sulphur in tetrathionate ion. B-8. The bond angle in PH4+ is higher than that in PH3. Why ? B-9. Write the oxyacids of the following : Oxide N2O3 Oxyacids NO2/N2O4 N2O5 P4O6 P4O10 B-10. N2, CO, CN– and NO+ are isoelectronic but the former is chemically inert and latter three are very reactive, why ? B-11. On moving down the group from H2O to H2Te acidic strength increases, why ? Section (C) : Preparation & Properties of elements C-1. What happens when barium azide is heated ? C-2. Which stable elements of 15th and 16th group do not react with water under normal conditions ? C-3. Chemiluminescence is a phenomenon in which on element glows in dark when exposed to moisture. Which element of 15th group shows this phenomenon ? p-block elements (N & O Family) Section (D) : Hydrides D-1. Among the hydrides of group 16, water shows unusual boiling point. Why ? D-2. Ammonium salts generally resemble those of potassium and rubidium in solubility & structure. Give reason D-3. Write balanced equation when NH3 is dissolved in (a) water (b) HCl (c) aq. CO2 D-4. What happens when phosphine is absorbed in mercuric chloride solution ? D-5. On being slowly passed through water, PH3 forms bubbles but NH3 dissolves. Why is it so ? D-6. How is hydrazine prepared ? D-7. Both PH3 and NH3 are Lewis bases, but basic strength of PH 3 is less than that of NH3. Explain Section (E) : Oxides E-1. In the preparation of P4O6, a mixture of N2 and O2 is used rather than pure O2, Why ? E-2. A compound of 15th group element is used as a fast drying agent in the laboratory. It is : E-3. Write the structures of the oxides : N2O3, N2O5, P4O6 and P4O10. E-4. Why does NO2 dimerise ? Section (F) : Oxyacids F-1. In the manufacture of sulphuric acid by the contact process, sulphur trioxide is not directly dissolved in water. Why ? F-2. How are SO2Cl2.SO3 and SO2 obtained from sulphuric acid ? F-3. Sulphur on oxidation with hot sulphuric acid gives : Section (G) : Halides and Oxyhalides G-1. Pentahalides of phosphorus are known, but not pentahydride. Why ? G-2. A compound ‘X’ which is a yellowish white powder is prepared by the reactions of white phosphours with excess of dry Cl2. Identify ‘X’ : G-3. Which hydride of the oxygen family shows the lowest boiling point? G-4. What happens when (A) PCl5 is heated. (B) PCl5 is reacted with heavy water. G-5. Why does PCl3 fume in moist air ? G-6. Complete and balance the following : (i) P4O10 + PCl5 ⎯→ Gelatin ⎯ → (ii) NH3 + NaOCl ⎯⎯⎯ Section (H) : Miscellaneous Compounds H-1. NaHSO3 + [X] (excess) + H2O ⎯→ NaHSO4 + HI [X] + Na2S2O3 ⎯→ NaI + [Y] Identify X & Y ? H-2. Identify the product of the given reaction : AgBr + 2Na2S2O3 ⎯→ H2SO4 (dil) + Na2S2O3 ⎯→ H-3. H2SO4 (conc.) + Na2S2O3 ⎯→ A and B are elements with atomic numbers 16 and 17. Write different combinations of binary compounds known from them. p-block elements (N & O Family) PART - II : ONLY ONE OPTION CORRECT TYPE Section (A) : Occurence, Atomic & Physical properties. A-1. Which of the following is least reactive ? (A) White phosphorus (B) Yellow phosphorus (C) Red phosphorus (D) Black phosphorus A-2. Nitrogen is best obtained by the thermal decomposition of which one of the following : (A) NH4Cl (B) NH4NO3 (C) AgNO3 (D) NH4NO2 A-3. In modern process, white phosphorus is manufactured by : (A) heating a mixture of phosphorite mineral with sand and coke in an electric furnace (B) heating calcium phosphate with lime (C) heating bone ash with coke (D) heating phosphate mineral with sand. Section (B) : General trends & Chemical Properties. B-1. The oxidation state of sulphur in the anions SO32–, S2O42– and S2O62– follows the order : (A) S2O62– < SO42– < SO32– (B) S2O42– < SO32– < S2O62– 2– 2– 2– (C) SO3 < S2O4 < S2O6 (D) S2O42– < S2O62– < SO32– B-2. Correct statement about allotropy of sulphur is : (A) Monoclinic sulphur is more stable than Rhombic sulphur at room temperature. (B) Both Monoclinic and Rhombic sulphur have same ring structures and crystalline structure. (C) Rhombic sulphur exists at room temperature. (D) None of these B-3. The nitrogen atom may complete its octet in several ways. Which one is incorrect ? (A) Electron gain to form the nitride Ion, N3– e.g. Li3N. (B) Formation of electron pair bonds. e.g. NH3 or NF3 Azo compounds (–N=N–) (C) Formation of electron - pair bonds with electron gain. e.g. Amide ion NH2– and imide ion NH2–. (D) Formation of electron pair bonds with electron gain : NH4+ ; N2H5+; (C2H5)4 N+ B-4. + 4 Ammonium NH , NH3 , NH2– , NH2– and N3 – are : Ammonia Amide Imide Nitride (A) Isoelectronic (C) Homologous members B-5. (B) Isostructural (D) Nitrogen has different oxidation state How many P=O bonds are present in (HPO3)3 ? (A) 0 (B) 6 (C) 3 (D) 9 B-6. The correct order of sulphur − oxygen bond energy in S2O32−, SO42−, SO3 and S2O62− is (A) S2O32− < SO42− < SO3 < S2O62− (B) S2O32− < S2O62− < SO42− < SO3 2− 2− 2− (C) S2O3 < SO4 < S2O6 < SO3 (D) S2O62− < SO42− < SO3 < S2O32− B-7. Which of the following bonds has the highest bond energy ? (A) Se−Se (B) Te−Te (C) S−S B-8. The wrong statement about N2O is : (A) it is nitrous oxide (C) it is not a linear molecule (B) it is a neutral oxide (D) it is known as laughing gas B-9. The hydrides of group 15 elements can act as : (A) lewis acid (B) lewis base (C) both B-10. (D) O−O The basic strength of the hydrides of group 15 elements : (A) decreases on moving down the group (B) increases on moving down the group (C) first decreases upto AsH3 and then increases (D) first increases upto AsH3 and then decreases (D) none p-block elements (N & O Family) Section (C) : Preparation & Properties of elements C-1. Ammonium salts decompose quite readily on heating : heat → Gas X (i) Ammonium salt of weak oxidizing anion (e.g. Cl–, CO32–, SO42–) ⎯⎯⎯ heat – – – → Gas Y/Z (ii) Ammonium salt of strong oxidizing anion (e.g. NO 2 , NO3 , ClO4 , Cr2O72–) ⎯⎯⎯ Identify X, Y, Z (A) N2, NH3, N2O (B) NH3, N2, N2O (C) N2O, NH3, N2 (D) NO, NH3, N2O C-2. Which of the following does not give oxygen on heating ? (A) (NH4)2Cr2 O7 (B) KClO3 (C) Zn(ClO3)2 (D) K2Cr2O7 C-3. Red and white phosphorus will differ but not in : (A) smell (B) solubility in CHCl3 (C) exhibiting phosphorescence (D) reaction with concentrated HNO3 C-4. Which of the following is incorrect ? (A) Ammonia is prepared in the laboratory by the action of NaOH on Ammonium salt. (B) All the hydrides of 15th group are colourless, highly volatile and poisonous gases (C) Metal phosphides upon hydrolysis give phosphine. (D) Metal phosphides upon hydrolysis give phosphoric acid. C-6. warm → Products P4 + NaOH ⎯⎯⎯ Products will be : (A) H3PO4 + PH3 (C) NaH2PO2 + H3PO4 (B) PH3 + NaH2PO2 (D) H3PO4 C-7. Hydrolysis of Nitride of s-Block elements (for e.g. Ba3N2, Ca3N2, Li3N) will yield (A) NH3 + Metal hydroxide (B) only NH3 (C) NH3 + HNO3 (D) NH4OH Section (D) : Hydrides D-1. The thermal stability of the hydrides of group 15 follows the order : (A) NH3 < PH3 < AsH3 < SbH3 < BiH3 (B) NH3 > PH3 > AsH3 > SbH3 > BiH3 (C) PH3 > NH3 > AsH3 > SbH3 < BiH3 (D) AsH3 < PH3 > SbH3 > BiH3 > NH3 D-2. One mole of calcium phosphide on reaction with excess water gives : (A) one mole of phosphine (B) two moles of phosphoric acid (C) two moles of phosphine (D) one mole of phosphorus pentoxide D-3. H2S burns in O2 to form (A) H2O + S (B) H2O + SO2 D-4. PH3 (anhydrous) + HBr (anhydrous) ⎯→ X. (A) H3BrO3 (B) PH4Br D-5. (C) H2O + SO3 (D) H2SO4 + S Identify X ? (C) Br2 (D) P4 Calcium phosphide reacts with water or dil. HCl and gives a compound ‘X’, which fails to react with HCl but produces dense white fumes with HI (g) due to formation of ‘Y’. Compound X and Y respectively. (A) X = PH3 and Y = PH4I (B) X = NaH2PO2 and Y = H3PO2 (C) X = PH4+ and Y = PH4I (D) X = PH3 and Y = H3PO2 O +H O 2 2 2 2 ⎯ → Y ⎯⎯⎯⎯ D-6. N2 ⎯⎯⎯⎯⎯→ X ⎯⎯⎯⎯⎯ →Z H O Haber ' s Pr ocess Ostwald' s Pr ocess Identify X, Y, Z (A) NH3, NO2, HNO3 (B) NH3, NO, HNO3 (C) NO2, NH3, HNO2 (D) NH3, NO, HNO2 Section (E) : Oxides E-1. Sulphur trioxide can be obtained by which of the following reactions :   → → (A) S + H2SO4 ⎯⎯ (B) H2SO4 + PCl5 ⎯⎯   (C) CaSO4 + C ⎯⎯→ (D) Fe2(SO4)3 ⎯⎯→ E-2. NO2 can be prepared by heating : (A) NH4NO3 (B) NaNO3 (C) Pb(NO3)2 (D) KNO3 p-block elements (N & O Family) E-3. HNO3 + P4O10 ⎯→ HPO3 + X in the above reaction the product X is : (A) NO2 (B) N2O3 (C) N2O4 (D) N2O5 E-4. Which of the following oxides of Nitrogen is Neutral (A) N2O5 (B) N2O3 (C) N2O4 (D) N2O E-5. Which of the following oxides is amphoteric in nature ? (A) N2O3 (B) P4O6 (C) Sb4O6 (D) Bi2O3 E-6. Following are neutral oxides except : (A) NO (B) N2O (C) CO (D) NO2 E-7. Aqueous solution of SO2 is a : (A) weak acid (B) reducing agent (C) bleaching agent (D) All of these E-8. Which of the following oxides is the most acidic ? (A) N2O5 (B) P2O5 (C) As2O5 (D) Sb2O5 Section (F) : Oxyacids F-1. The correct order of decreasing acidic strength of oxy acids of group 15 elements : (A) HNO3 > H3SbO4 > H3AsO4 > H3PO4 (B) H3PO4 > H3AsO4 > H3SbO4 > HNO3 (C) HNO3 > H3PO4 > H3AsO4 > H3SbO4 (D) HNO3 > H3AsO4 > H3PO4 > H3SbO4 F-2. Industrial preparation of nitric acid by ostwald’s process involves : (A) oxidation of NH3 (B) Reduction of NH3 (C) Hydrogenation of NH3 (D) Hydrolysis of NH3 F-3. Which of the following is the most powerful oxidising agent : (A) H2SO4 (B) HPO3 (C) H3BO3 F-4. F-5. When P4O10 is dissolved in water, the acid formed finally is : (A) H3PO2 (B) H3PO4 (C) H3PO3 (D) H3PO4 (D) H4P2O7 Which of the following reactions depict the oxidising behaviour of H2SO4 ? (A) 2PCl5 + H2SO4 ⎯→ 2POCl3 + 2HCl + SO2Cl2 (B) 2NaOH + H2SO4 ⎯→ Na2SO4 + 2H2O (C) NaCl + H2SO4 ⎯→ NaHSO4 + HCl (D) 2H + H2SO4 ⎯→ 2 + SO2 + 2H2O Section (G) : Halides and Oxyhalides G-1. The order of stability of halides of sulphur with different halogens is : (A) I– > Br– > Cl– > F– (B) F– > Cl– > Br– > I– (C) Br– > Cl– > I– > F– (D) F– > Cl– > I– > Br– G-2. Ammonia reacts with excess of chlorine to form : (A) N2 and NH4Cl (B) NCl3 and HCl (C) NH4Cl and NCl3 (D) N2 and HCl G-3. A yellow coloured crystalline substance gave a colourless gas X on reaction with flourine, which is thermally stable and has octahedral geometry. X can be. (A) SF4 (B) SF6 (C) SF2 (D) S2F6 G-4. PCl3 reacts with water to form : (A) PH3 (B) H3PO3 and HCl (C) POCl3 (D) H3PO4 G-5. The final product obtained on hydrolysis of PCl5 is : (A) H3PO4 (B) H3PO3 (C) POCl3 (D) PH3 G-6. Which of the following phosphorus halide is the best reducing agent? (A) PCl3 (B) PF3 (C) PBr3 (D) P3 Section (H) : Miscellaneous Compounds H-1. When sulphur is boiled with Na2SO3 solution, the compound formed is : (A) sodium sulphide (B) sodium sulphate (C) sodium persulphate (D) sodium thiosulphate p-block elements (N & O Family) H-2. Na2S2O3 is prepared by : (A) reacting H2S2O3 with NaOH. (C) heating NaOH and S. (B) reacting Na2SO4 with S in alkaline medium. (D) reducing Na2SO4 with S in acidic medium. H-3. The products of the chemical reaction between Na 2S2O3, Cl2 and H2O are : (A) HCl + Na2S (B) HCl + NaHSO4 (C) HCl + Na2SO3 (D) NaHClO3 + H2O H-4. The term 'thio' is used in the names of all of the following compounds except : (A) Na2S2O3 (B) Na2S2O6 (C) NaSCN (D) Na2SO3 H-5. Which of the following gives H2O2 on hydrolysis ? (A) H2S2O3 (B) H2SO5 (C) H2S2O7 (D) H2S4O6 Which of the following is not formed in the below reaction : O3 + KI + D2O ⎯→ (A) KOH (B) O2 (C) I2 (D) KOD H-6. PART - III : MATCH THE COLUMN 1. Match the reactions listed in column-I with characteristic(s) / type of reactions listed in column-II. Column–I Column–II Moist (A) (p) Hydrolysis PCl5 ⎯⎯⎯→ Air 2. (B) Warm → P4 + NaOH (conc.) + H2O ⎯⎯⎯ (q) (C) 200ºC H3PO3 ⎯⎯⎯→ (r) At least one of the products has tetrahedral hybridisation Disproportionation (D) 200ºC P4O6 + H2O ⎯⎯⎯→ (s) At least one of the products has p–d bonding. Match the oxy-acids of phosphorus listed in column-I with type of bond(s) listed in column-II. Column-I Column-II (Oxy acids of phosphoros) (Characteristic bonds) (A) H4P2O7 (p) P—P bond (s) (B) H4P2O5 (q) P—O—P bond (s) (C) H3P3O9 (r) P—H bond (s) (D) (HPO3)n (cyclic) (s) Three or four P—OH bonds  Marked questions are recommended for Revision. PART - I : ONLY ONE OPTION CORRECT TYPE 1. In case of nitrogen, NCl3 is possible but not NCl5 while in case of phosphorous, PCl3 as well as PCl5 are possible. It is due to (A) Availability of vacant d-orbital in P but not in N (B) Lower electronegativity of P than N (C) Lower tendency of H bond formation in P than N (D) Occurrence of P in solid while N in gaseous state at room temperature. 2. The P-P-P bond angle in white phosphorus is close to : (A) 120º (B) 109º28’ (C) 90º 3. (D) 60º Red phosphorus can be prepared from white phosphorus by : (A) adding red colour to white phosphorus (B) heating white phosphorus to red heat (C) heating white phosphorus in inert atmosphere to 250ºC or at low temperature in the presence of sun light. (D) heating white phosphorus at high pressure and 473 k temperature. p-block elements (N & O Family) 4. As Rhombic sulphur is heated in a test tube : Process (a) Viscosity increases (b) Viscosity decreases (c) Paramagnetic molecules (d) Breakage of S8 rings (Diradical formation in molten phase) Correct order of temperature is : (A) T1 < T3 < T4 < T2 (B) T2 < T4 < T3 < T1 Temperature T1 T2 T3 T4 (C) T4 < T1 < T2 < T3 (D) T3 < T4 < T1 < T2 5. Dinitrogen gas is evolved when sodium nitrite is heated below 500ºC : (A) alone (B) with ammonium chloride (C) with sodium chloride (D) with potassium nitrate 6. Which statement is not correct for nitrogen ? (A) It is obtained by heating (NH4)2Cr2O7 (C) It is a typical non-metal (B) It does not readily react with O2 (D) d-orbitals are available for bonding Nitrolim is obtained by passing nitrogen over : (A) heated mixture of Al2O3 and carbon (C) calcium carbide (B) oleum (D) heated calcium carbide Which of the following have Hºf < 0 : (A) Ozone (B) O (g) (C) P (red) CS2 can separate a mixture of : (A) P4 and S8 (rhombic) (C) S8 (rhombic) and S8 (monoclinic) (B) P4 and S8 (monoclinic) (D) S8 (rhombic) and S (plastic) 7. 8. 9. (D) S8 (monoclinic) 10. Which of the following reactions does not liberate oxygen ? (A) O3 + KI + H2O ⎯→ (B) H2O2 + Cl2 ⎯→ (C) KO2 (s) + CO2 (g) ⎯→ (D) None 11. The gas respectively absorbed by alkaline pyrogallol and oil of cinnamon is : (A) O2, O3 (B) SO2, O2 (C) O3, CH4 (D) N2O, O3 12. Alkaline K is oxidised by ozone to : (A) potassium iodate (C) both (A) and (B) (B) potassium periodate (D) None of these NH3 can't be obtained by : (A) heating of NH4NO3 or NH4NO2 (C) heating of NH4NO3 with NaOH (B) heating of NH4Cl or (NH4)2 CO3 (D) reaction of AIN or Mg3N2 or CaCN2 with H2O 13. 14. When H2S is passed through nitric acid or acidified KMnO4 solution, the product first formed is : (A) H2SO4 (B) colloidal sulphur (C) SO2 (D) plastic sulphur 15. Ammonia and red hot CuO react to produce : (A) Cu2O, N2, H2 (B) Cu, H2O, N2 16. 17. 18. (C) Cu(OH)2, N2 (D) [Cu(NH3)4](OH)2 Phosphine is not obtained by the reaction : (A) White P is heated with NaOH (B) Red P is heated with NaOH (C) Ca3P2 reacts with water (D) Phosphorus trioxide is boiled with water under pressure. When ammonia is oxidsed by oxygen in the presence of platinum at 500ºC, the gas obtained is : (A) N2O (B) NO (C) NO2 (D) N2O5 Substances burn more readily in N2O than in air because N2O : (A) is reactive at high temperature. (B) dissociates to give more nitrogen than in air. (C) the activation energy is increased on increasing temperature. (D) dissociates more readily than O2. p-block elements (N & O Family) 19. Which of the following is a mixed acid anhydride ? (A) NO (B) NO2 (C) N2O5 (D) N2O 20. When an article is bleached by SO2 it loses its colour. The colour can be restored by : (A) exposure to air (B) heating (C) dilution (D) none of these 21. The true statement for the acids of phosphorus H3PO2, H3PO3 and H3PO4 is. (A) H3PO3 on heating does not disproportionate (B) all of them are reducing in nature (C) all of them are tribasic acids (D) H3PO2 is obtained by alkaline hydrolysis of P4 (white) 22. Which of the following does not have S–S linkage but has O—O linkage ? (A) S2O82– (B) S2O62– (C) S2O52– (D) S2O32– 23. The true statement for the acids of phosphorus H3PO2, H3PO3 and H3PO4 is : (A) the order of their reducing strength is H3PO2 > H3PO3 > H3PO4. (B) the hybridisation of phosphorus is sp2 in all these. (C) The acidic strength order is H3PO2 > H3PO3 > H3PO4. (D) all of these. 24. Hydrolysis of one mole of peroxydisulphuric acid produces (A) two moles of sulphuric acid (B) two moles of peroxymonosulphuric acid. (C) one mole of sulphuric acid and one mole of peroxy monosulphuric acid. (D) one mole of sulphuric acid, one mole of hydrogen peroxide. 25. The reaction of SO2 with PCl5 yield two oxohalides A and B. ‘A’ can also be prepared industrially by reaction of SO3 and SCl2. Which of the following about A and B is incorrect ? (A) The structure of B is tetrahedral (B) The structure of A is trigonal pyramidal (C) A reacts vigorously with water and is particularly useful for drying or dehydrating readily hydrolysable inorganic halides (D) A and B contain their respective central atoms in their highest oxidation states. 26. Which of the following cannot dissociate as PX5 PX3 + X2 (A) PF5 (B) PCl5 (C) PBr5 27. The aqueous solution of hydrogen peroxide : (A) converts blue litmus pink (C) converts red litumus blue (D) PI5 (B) converts blue litumus white (D) None of these 28. Consider the following compounds : (1) sulphur dioxide (2) hydrogen peroxide (3) ozone Among these compounds, those which can act as bleaching agents would include : (A) 1 and 3 (B) 2 and 3 (C) 1 and 2 (D) 1, 2 and 3 29. Bleaching of a fabric cloth is done using A and excess of chlorine is removed using B. A and B are : (A) CaOCl2 , Na2SO3 (B) Na2S2O3 , CaOCl2 (C) CaCl2 , Na2S2O3 (D) CaOCl2 , Na2S2O3 30. Aqueous hypo solution on reaction with aqueous AgNO 3 gives : (A) yellow precipitate changing to black (B) white precipitate changing to black (C) orange precipitate to blue (D) no precipitate p-block elements (N & O Family) PART - II : SINGLE AND DOUBLE VALUE INTEGER TYPE 1. What is the sum of highest and lowest oxidation states for oxygen family. 2. How many of the following is correct order of specified property. (a) N > P > As > Sb > Bi (First ionisation enthalpy) (b) N > P > As > Sb (Electronegativity) (c) N–N < P–P < As–As (Single bond length) 3+ 3+ 3+ (d) As > Sb > Bi (Stability of +3 oxidation state) (e) White > Red > Black (Reactivity of allotropes of phosphorus) (f) H3PO2 < H3PO3 < H3PO4 (Proticity of acids) (g) H3PO2 < H3PO3 < H3PO4 (Reducing power of acids) 3. How many of the following properties increase down the group for nitrogen family. (a) Atomic size (b) Acidic character of oxides (c) Boiling point of hydrides (d) Reducing power of hydrides (e) Extent of p-p overlap. (f) Metallic character. (g) Basic character of hydrides 4. Given below are some properties. How many of these can hold good for phosphorous. (a) Metal (b) Non-metal (c) Metalloid (d) Exhibits allotropy (e) Catenation property (f) Solid (g) Good conductor of electricity (h) Least dense among nitrogen family elements. 5. Below reaction sequence illustrates the various stages of reduction of nitric acid where a, b, c, d are the number of electrons involved in the reduction of 1 mole N-atoms. → NO2 ⎯⎯⎯ → NO ⎯⎯⎯ → N2O ⎯⎯⎯ → NH3 HNO3 ⎯⎯⎯ ae − be − ce − de − Find the value of (2a + b + 3c – d). 6. A yellow coloured crystalline element gives a colourless gas (X) on reaction with fluorine which is thermally stable & has octahedral geometry. The atomicity of compound (X) would be.... 7. Sulphur can form dihalide, tetrahalide and hexahalide with fluorine. One mole of each of these three compounds is mixed with water. The total number of moles of product molecules obtained is____. If no reaction occurs, count zero. 8. Number of halides undergoing complete reaction in presence of water under normal conditions is : (i) BF3 (ii) BCl3 (iii) NCl3 (iv) AlCl3 (v) CCl4 (vi) PCl3 (vii) AsCl3 9. In how many of the following reactions N2 gas may be released  (a) NH4NO2 ⎯⎯ → (d) NH2CONH2 + NaOBr ⎯→  (b) (NH4)2Cr2O7 ⎯⎯ → (e) NH3 + Cl2 (LR) ⎯→  (c) NH2CONH2 + HNO2 ⎯⎯ → (f) NH3 + Br2 (LR) ⎯→ (g) NH3 + NaOCl ⎯→ (h) NH3 + CaOCl2 ⎯→  (i) Ba(N3)2 ⎯⎯ → 10. (i) NH3 (ii) N2H4 (iii) HN3 (iv) PH3 (v) H2S (vi) AsH3 (vii) SbH3 (viii) H2Se (ix) H2Te Number of molecules in which lone pair of electrons on the central atom is present in pure s-orbital. 11. gelatin or EDTA NH3 + NaOCl ⎯⎯⎯⎯⎯⎯⎯ → products The number of moles of N–H bonds present in one mole of the strongest nucleophile present in the product is : 12. Number of acidic oxides among the following is : (a) N2O (b) NO (c) N2O3 (d) N2O4 (g) P4O10 (h) SO3 (i) B2O3 (j) CO 13. 4− (e) N2O5 (f) P4O6 Number of gaseous oxides among the following at room temperature is : (a) N2O (b) NO (c) N2O3 (d) NO2 (e) N2O5 (g) P4O10 (h) SO2 (i) SO3 (f) P4O6 p-block elements (N & O Family) 14. The number of O-atoms having sp2 hybridisation in P4O10 molecule is : 15. N2O4, (HPO3)3, H2CO3, SO2, SO3, P4O10 H2SO4, N2O3, HNO3, H3PO3. (a) Among the above compounds, compounds having at least one p-p bond are x. (b) Among the above compounds, compounds having at least one d-p bond are y. Give the answer as x + y. 16. Number of acids having central atom in +3 oxidation state among the following is : (a) HNO2 (b) HNO3 (c) H3PO2 (d) H3PO3 (e) H3PO4 (f) H4P2O5 (g) H4P2O7 (h) H2SO3 (i) H2S2O7 (j) H2S2O8 (k) H2SO4 17. Cold conc. HNO3 will completely dissolve : (i) Pb (ii) Pb3O4 (iii) Fe (vii) Hg (viii) Au (ix) Ag 18. 19. (iv) Sn (x) Pt. (v) Mg (vi) MgO Cold dil. H2SO4 will completely dissolve : (i) Pb (ii) Fe3O4 (iii) Fe (vii) CoCO3 (viii) CuCO3 (ix) SrCO3 (iv) Cu (v) Mg (vi) MgO How many are redox reactions  → (i) K4[Fe(CN)6] + conc. H2SO4 ⎯⎯ (iii) conc. H2SO4 + KBr ⎯→ (v) conc. H2SO4 + KNO3 ⎯→ (vii) conc. H2SO4 + COCl2 ⎯→ (ix) conc. H2SO4 + Cu ⎯→ (ii) conc. H2SO4 + KCl ⎯→ (iv) conc. H2SO4 + NH3 ⎯→ (vi) conc. H2SO4 + PCl5 ⎯→ (viii) conc. H2SO4 + Zn ⎯→ 20. x P4 + y SO2Cl2 ⎯→ then y/x ? 21. Complete hydrolysis product of 1 mole each of following will need how many total number of moles of NaOH for complete neutralisation? SOCl2 , SO2Cl2 , PCl3 , PCl5 , NCl3 22. Aqueous solution of how many of the following species turn blue litmus red ? (i) SF4 (ii) PCl3 (iii) N2O (iv) NO2Cl (v) SF6 (vii) AsCl3 (viii) POCl3 (ix) SO2 (x) SO2Cl2 (xi) SOCl2 (xiii) CCl4 (vi) SeF6 (xii) COCl2 23. How many of the following compounds are possible products when chlorine is passed through hypo solution. (i) S (ii) HCl (iii) Na2S (iv) Na2SO4 (v) Na2S4O6 (vi) HClO4 24. The difference in oxidation states of sulphur atoms (in different oxidation states) present in Na 2S4O6 is : 25. How many compound(s) or ion(s) can be oxidised by H2O2 among the following : (i) AsO33– (ii) SO42– (iii) Fe2(SO4)3 (iv) NH2–NH2 (v) H2S (vi) PbS (vii) O3 26. A gas is pale blue in colour on liquifaction, the colour arises from electronic transitions. This transition is forbidden in gaseous state. The gas does not burn but is a strong supporter of combustion. Give the molar mass of this gas. PART - III : ONE OR MORE THAN ONE OPTIONS CORRECT TYPE 1. As, Sb and Bi show lesser tendency to form negative ions of the type M3–. This is because (A) these elements are less electronegative (B) metallic character increases down the group (C) they are unable to hold the added electrons due to inert pair effect (D) they do not posses half filled np subshells p-block elements (N & O Family) 2. The correct statement(s) is/are : (A) The PF6– ion exists (B) The NF6– ion does not exist (C) N can form p-p bonds with itself and with other elements having small size and high E.N. (D) The catenation tendency is weaker in N than P 3. Correct statements about allotropy ? (A) Plastic sulphur exists as zig-zag chains of sulphur. (B) Monoclinic sulphur is soluble in water and insoluble in CS2. (C) Milk of sulphur gradually changes to Rhombic sulphur. (D) Milk of sulphur is used in medicines. 4. Which of the following statements is/are correct ? (A) The hydrides of group 15 elements act as oxidising agents (B) The hydrides of group 15 elements act as reducing agents (C) The oxidising power increases in going from NH3 to BiH3 (D) The reducting power increases in going from NH3 to BiH3 5. Ammonium dichromate on heating liberates a gas. The same gas will be obtained by : (A) heating NaNO2 and NH4Cl. (B) treating H2O2 with NaNO2 . (C) passing ammonia gas over red hot CuO. (D) treating ammonia with KMnO4 in neutral medium. 6. Nitrogen differs from rest of the members on the account of various factors. Which of the following properties can be classified as anomalous properties of nitrogen ? (A) Bond enthalpy of NN is 941.4 kJ/mol. (B) Hydride of nitrogen i.e. ammonia has appreciable boiling point as compared to the other members like P, As. (C) NH3 can form unstable complexes by donating its lone pair. (D) Molecular nitrogen comprises 78% by volume of the atmosphere. 7. Which of the following elements react with metals to form their binary compounds exhibiting –3 oxidation state ? (A) N (B) P (C) As (D) Bi 8. White phosphorus may be removed from red phosphorus by : (A) sublimation under reduced pressure (B) dissolving in water (C) dissolving in CS2 (D) heating with an alkali solution 9. The compound(s) which on strong heating gives oxygen is/are : (A) AgNO3 (B) BaO2 (C) Pb(NO3)2 (D) CaCO3 10. Which of the following is/are true for oxygen. (A) KMnO4(s) on strong heating gives oxygen gas (B) Oxygen mixed with helium is used for artificial respiration. (C) It has two unpaired electrons in bonding  molecular orbitals. (D) Fractional distillation of liquefied air is used as an industrial method for the preparation of oxygen gas. 11. The correct statements(s) regarding hydrides (H2E) of group-16 is/are : (A) The acidic character increases from H2O to H2Te. (B) The bond (H-E) dissociation enthalpy decreases down the group. (C) The thermal stability of hydrides decreases down the group (D) The reducing character of hydrides increases down the group 12. The correct statements regarding ozone is/are (A) Ozone is thermodynamically less stable with respect to oxygen (B) It acts as powerful oxidising agent (C) It rapidly react with NO(g) and form NO2(g) and O2(g) (D) It is toxic substance p-block elements (N & O Family) 13. The incorrect statement(s) regarding oxides of group-16 elements is/are (A) Reducing property of dioxide decreases from SO2 to TeO2 (B) All these elements form oxides of the EO2 and EO4 types (C) Selenium and tellurium do not form SeO3 and TeO3 (D) SO2 is an oxidising agent while TeO2 is a reducing agent. 14. Which of the following ions dissolve in excess of aq. NH3. (A) Al3+ (B) Cu2+ (C) Ag+ 15. Which of the following is/are incorrect statement(s) for phosphine ? (A) It is less basic then NH3 (B) It is less poisonous than NH3 (C) The solution of copper sulphate gives no precipitate with PH 3. (D) Phosphine burns in air forming predominantly H3PO4. 16. Which of the following process(es) can give sulphur ? (A) H2S gas is passed through nitric acid. (B) Cl2 gas is passed into water saturated with hydrogen sulphide. (C) Hydrogen sulphide is passed through sodium bisulphate solution. (D) H2S gas is passed through acidified KMnO4 solution. 17. How is H2S prepared in laboratory ? (A) FeS + H2SO4 (C) FeS + HCl (D) Zn2+ (B) FeSO4 + H2SO4 (D) Elemental H2 + elemental S8 18. A gas is obtained on heating ammonium nitrate. Which of the following statements are incorrect about this gas : (A) causes laughter (B) brings tears to the eyes (C) is acidic in nature (D) is basic in nature 19. Which of the following represents correct dissociation of nitrate salts on heating. 1 1 (A) 2LiNO3 ⎯→ Li2O + 2NO2 + O2 (B) Pb(NO3)2 ⎯→ PbO + 2NO2 + O2 2 2 (C) NH4NO3 ⎯→ N2O + 2H2O (D) NH4NO2 ⎯→ N2 + 2H2O 20. SO2 can reduce : (A) HClO3 to HCl (B) Cr2O72– / H+ to Cr3+ (C) MnO4– / H+ to Mn2+ (D) IO3– to I2 21. A white crystaline oxide (A) having garlic smell reacts with cold water to form a compound (B). On heating, (B) gives compound (C) & gas (D). Which of the following are correct statements : (A) Solution of gas (D) does not turn red litmus blue (B) The gas (D) can also be produced by reaction of NaOH with red phosphorus (C) Gas (D) exists in dimeric form. (D) Compound (B) can act as a reducing agent but (C) cannot. 22. Select the correct statement. (A) Ostwald's method of preparation of HNO3 is based upon catalytic oxidation of NH 3 by atmospheric oxygen. (B) HNO2 can act as both oxidising and reducing agent. (C) NO2 reacts with O3 to form N2O5. (D) HNO3 can be used both as oxidising and reducing agent. 23. Which of the following statements is (are) correct ? (A) Antimony on reaction with conc. HNO3 gives antimonic acid. (B) Manganese on reaction with cold and dilute HNO3 gives NO2 gas. (C) HNO2 disproportionate to give HNO3 and NO (D) HNO3 on reaction with P4O10 gives N2O5 24. Concentrated sulphuric acid acts as (A) dehydrating agent (C) reducing agent (B) sulphonating agent (D) oxidising agent. p-block elements (N & O Family) 25. Which among the following is/are peroxo acid (s) ? (A) H2S2O3 (B) H2SO5 (C) H2 S2 O7 (D) H2S2O8 26. Which of the following are used as chlorinating agents in organic synthesis of compounds ? (Like acid converted to acid chloride). (A) SOCl2 (B) SO2Cl2 (C) PCl3 (D) PCl5 27. Select the correct statement(s) regarding reaction of SO 2 with PCl5. (A) It is a redox reaction. (B) One of the product is sulphuryl chloride. (C) Both the products on addition of water produce strongly acidic solutions. (D) Both the products have same hybridisation of central atom. 28. CuSO4 NaH (P) ⎯⎯⎯ → (Q)  ⎯⎯⎯⎯ → (R)  black precipitate, (P) may be : (A) SCl2 (B) PCl3 (C) NCl3 (D) HCl 29. What is true for hydrogen peroxide and ozone ? (A) H2O2 acts as a stronger reducing agent in alkaline medium than in acidic medium (B) H2O2 and O3 both are oxidising agents as well as bleaching agents (C) H2O2 forms a hydrate, H2O2.H2O (D) Ozone is used in the manufacture of potassium permangnate from pyrolusite. 30. Which of the following statement (s) is/are true for sodium thiosulphate ? (A) it acts as an antichlor (B) it is used as a reducing agent in iodometric titration. (C) it reacts with hydrochloric acid to form SO2 and sulphur. (D) it is used in photography as hypo to dissolve excess of AgBr as a soluble complex. 31. Which of the following statements are correct for H2O2 ? (A) It is neutral towards litmus, but bleaches litmus white. (B) It is more acidic than H2O. (C) Density and dielectric constant are higher than dilute solution of H 2O. (D) H2O2 is produced by auto oxidation of 2-ethyl anthraquinol. 32. A solution of ammonia in water contains which of the following species : (A) H+ (aq.) (B) OH– (aq.) (C) NH4+ (aq.) (D) NH3 (aq.) PART - IV : COMPREHENSION Read the following passage carefully and answer the questions. Comprehension # 1 Nitrogen forms the largest number of oxides as it is capable of forming stable multiple bonds with oxygen. They range from N2O (O.S of nitrogen +1) through NO, N2O3, NO2, N2O4 to N2O5 (O.S of nitrogen +5). Following points are important regarding the study of oxides of nitrogen. (a) All oxides of nitrogen except N2O5 are endothermic as a large amount of energy is required to dissociate the stable molecule of oxygen and nitrogen. (b) The small electronegativity difference between oxygen and nitrogen make N–O bond easily breakble to give oxygen and hence oxides of nitrogen are said to be better oxidising agents. (c) Except N2O5, all are gases at ordinary temperature. N2O3 is stable only at lower temperature (253 K). (d) Except N2O and NO which are neutral oxides, all are acidic oxides which dissolve in water forming corresponding oxy acids. (e) They are also good example for illustrating the concept of resonance. 1. 2. The gas which is acidic in nature is : (A) NO (B) N2O (C) NO2 (D) both (A) and (C) Which of the following statements is correct for the oxides of nitrogen ? (A) Dinitrogen trioxide dissolves in potassium hydroxide forming potassium nitrate. (B) Aqueous solution of nitrogen dioxide behaves both as a reducing agent and as an oxidising agent. (C) Nitrous oxide is fairly soluble in cold water and turns blue litmus red. (D) Nitrogen dioxide is not acidic oxide. p-block elements (N & O Family) Comprehension # 2 An inorganic iodide (A) on heating gives gases (B) and (C). (B) is neutral towards litmus while (C) is acidic.(B) gives back dense white fumes of (A) when cooled with (C). (A) functions as a strong acid in water. (C) is also obtained by action of (D) on water. (D) can be obtained when (B) reacts with I 2 in presence of anhydrous CaCl2. (B) is poisonous, has smell of rotten fish and it is sparingly soluble in water. Now answer the following questions : 3. Select the correct statement from the following for the gas (B). (A) It produces dense white fumes with HCl (B) It produces dense violet fumes on combustion (C) It produces dense white fumes with BF3 (D) It can act as oxidising agent. 4. The compound (A) : (A) turns moist red litmus blue (C) is used as a dehydrating agent 5. (B) reacts completely with water (D) all of these What is true about compound (D) ? (A) The oxidation number of central atom of (D) is + IV (B) Compound (D) produces a yellow precipitate with silver nitrate solution. (C) Compound (D) dissolves in water forming an acid which with sodium hydroxide forms three series of salts. (D) Both (B) and (C) Comprehension # 3 Oxygen differs from the other elements of the group. Compounds of oxygen with metals are more ionic in nature and hydrogen bonding is more important for oxygen compounds. Oxygen is never more than divalent because when it has formed two covalent bonds, there are no low energy orbitals which can be used to form further bonds. However, the elements S, Se, Te and Po have empty d-orbitals which may be used for bonding, and they can form four or six bonds by unpairing electrons. The higher oxidation states become less stable on descending the group. The bond between S and O, or Se and O, are much shorter than might be expected for a single bond owing to p–d interaction between the p–orbital of oxygen and d - orbital of S or Se. 6. Which of the following statement is incorrect ? (A) Oxo-anions of sulphur have little tendency to polymerise compared with the phosphates and silicates. (B) In pyrosulphurous acid (H2S2O5), the oxidation states of both the sulphur atoms are not same, they are +V and +III (C) Concentrated HNO3 oxidises both sulphur and selenium to H2SO4 (+VI) and H2SeO4 (+VI) respectively. (D) Most metal oxides are ionic and basic in nature while non-metallic oxides are usually covalent and acidic in nature. 7. Which one of the following orders represents the correct order for the properties indicated against them? (A) H2O < H2S < H2Se < H2Te – acidic character (B) H2O < H2S < H2Se < H2Te – thermal stability (C) H2S > H2Se < H2Te < H2O – reducing character (D) H2S < H2Se < H2O < H2Te – boiling point Comprehension # 4 The property of hydrides of p–block elements mostly depends on : (i) electronegativity difference between central atom and hydrogen (ii) size of central atom (iii) number of valence electrons in central atom Some undergo hydrolysis in which central atom is less electronegative, react with OH – to give hydrogen. While acidic property of hydride in a period depends on electronegativity of central atoms, i.e. more electronegative is the atom, more acidic is hydride. n a group, acidic property is proportional to size of central atom. Some electron deficient hydride behaves as Lewis acid while only one hydride of an element in p–block behaves as Lewis base with lone pair of electrons. Hydrides in which central atom’s electronegativity is close to hydrogen has no reaction with water. 8. 9. Which one is the weakest acid among the following ? (A) HF (B) HCl (C) HBr (D) H Which hydride has no reaction with water ? (A) NH3 (B) CH4 (D) NaH (C) BeH2 p-block elements (N & O Family) 10. Which one is strongest base ? (A) OH– (B) HS– (C) HSe– (D) HTe– Comprehension # 5 Answer Q.11, Q.12 and Q.13 by appropriately matching the information given in the three columns of the following table. Observe the three columns in which column-1 represents chemical reactions, column-2 represents nature of substance with colour and physical state while column-3 represents differentiate products. Column-1 Column-2 Column-3 (I) Cu + dil. HNO3 (i) Colourless gas, Neutral (P) NO (II) Cu + conc. HNO3 (ii) Blue solid, Acidic (Q) NO2 (III) Zn + dil. HNO3 (iii) Brown gas, Acidic (R) N2O (IV) Zn + conc. HNO3 (iv) Colourless solid, Acidic (S) N2O3 11. 12. 13. Which of the following set of combination is correct ? (A) (I), (iv), (S) (B) (II), (ii), (Q) (C) (II), (iii), (Q) (D) (IV), (iv), (S) Which of the following set of combination is incorrect ? (A) (III), (i), (R) (B) (I), (i), (P) (C) (IV), (iii), (Q) (D) (III), (iv), (S) Which of the following set of combination is correct ? (A) (I), (ii), (P) (B) (IV), (iii), (Q) (C) (IV), (ii), (Q) (D) (I), (iii), (P) * Marked Questions may have more than one correct option. PART - I : (ADVANCED) / PROBLEMS (PREVIOUS YEARS) Section (A) : Group 15th 1. 2. 3. The number of P—O—P bonds in cyclic trimetaphosphoric acid is : (A) zero (B) two (C) three The correct order of acidic strength is : (A) Cl2O7 > SO2 > P4O10 (C) Na2O > MgO > Al2O3 (B) CO2 > N2O5 > SO3 (D) K2O > CaO > MgO Ammonia can be dried by : (A) conc. H2SO4 (B) P4O10 (C) CaO (D) four (D) anhydrous CaCl2 4. Give reason why elemental nitrogen exists as diatomic molecule whereas elemental phosphorus is a tetra-atomic molecule. 5. Polyphosphates are used as water softening agents because they : (A) form soluble complexes with anionic species (B) precipitate anionic species (C) form soluble complexes with cationic species (D) precipitate cationic species 6. For H3PO3 and H3PO4, the correct choice is : (A) H3PO3 is dibasic and reducing (C) H3PO4 is tribasic and reducing (B) H3PO3 is dibasic and non-reducing (D) H3PO3 is tribasic and non-reducing 7. (NH4)2 Cr2O7 on heating gives a gas which is also given by : (A) heating NH4NO2 (B) heating NH4NO3 (C) treating Mg3 N2 with H2O (D) treating Na(compound) with H2O2 8. A pale blue liquid is obtained by equimolar mixture of two gases at –30ºC. (A) N2O (B) N2O3 (C) N2O4 (D) N2O5 9. Thermodynamically most stable allotrope of phosphorus is : (A) Red (B) White (C) Black (D) Yellow (a) What amount of CaO in grams is required to neutralise 852 g of P4O10 . (b) Write the structure of P4O10. 10. p-block elements (N & O Family) Paragraph for Question Nos. 11 to 13 There are some deposits of nitrates and phosphates in earth’s crust. Nitrates are more soluble in water. Nitrates are difficult to reduce under the laboratory conditions but microbes do it easily. Ammonia forms large number of complexes with transition metal ions. Hybridization easily explains the ease of sigma donation capability of NH3 and PH3. Phosphine is a flammable gas and is prepared from white phosphorous. 11. Among the following, the correct statement is : (A) phosphates have no biological significance in humans. (B) between nitrates and phosphates, phosphates are less a abundant in earth’s crust. (C) between nitrates and phosphates, nitrates are less abundant in earth’s crust. (D) oxidation of nitrates is possible in soil. 12. Among the following, the correct statement is : (A) between NH3 and PH3, NH3 is a better electron donor because spherical ‘s‘ orbital and is less directional. (B) between NH3 and PH3, PH3 is a better electron donor because sp3 orbital and is more directional. (C) between NH3 and PH3, NH3 is a better electron donor because sp3 orbital and is more directional. (D) between NH3 and PH3, PH3 is a better electron donor because spherical ‘s’ orbital and is less directional. the lone pair of electrons occupies the lone pair of electrons occupies the lone pair of electrons occupies the lone pair of electrons occupies 13. White phosphorus on reaction with NaOH gives PH 3 as one of the products. This is a : (A) dimerization reaction (B) disproportionation reaction (C) condensation reaction (D) precipitation reaction 14. The reaction of P4 with X leads selectively to P4O6. The X is : (A) Dry O2 (B) A mixture of O2 and N2 (C) Moist O2 (D) O2 in the presence of aqueous NaOH 15. Match each of the reactions given in column-I with the corresponding products (s) given in column II. (A) (B) (C) (D) 16. Column-I Cu + dil HNO3 Cu + conc HNO3 Zn + dil HNO3 Zn + conc HNO3 (p) (q) (r) (s) (t) Column-II NO NO2 N2O Cu(NO3)2 Zn(NO3)2 Extra pure N2 can be obtained by heating (A) NH3 with CuO (B) NH4NO3 (C) (NH4)2Cr2O7 (D) Ba(N3)2 17. Among the following, the number of compounds that can react with PCl 5 to give POCl3 is O2, CO2, SO2, H2O, H2SO4, P4O10. 18. Which ordering of compounds is according to the decreasing order of the oxidation state of nitrogen? (A) HNO3, NO, NH4Cl, N2 (C) HNO3, NH4Cl, NO, N2 19. (B) HNO3, NO, N2, NH4Cl (D) NO, HNO3, NH4Cl, N2 Concentrated nitric acid, upon long standing, turns yellow-brown due to the formation of : (A) NO (B) NO2 (C) N2O (D) N2O4 20.* The pair(s) of reagents that yield paramagnetic species is/are (A) Na and excess of NH3 (B) K and excess of O2 (C) Cu and dilute HNO3 (D) O2 and 2-ethylanthraquinol 21. The product formed in the reaction of SOCl2 with white phosphorous is : (A) PCl3 (B) SO2Cl2 (C) SCl2 (D) POCl3 p-block elements (N & O Family) 22.* The compound(s) which generate(s) N2 gas upon thermal decomposition below 300ºC is (are) (A) NH4NO3 23.* (B) (NH4)2Cr2O7 (C) Ba(N3)2 (D) Mg3N2 Based on the compounds of group 15 elements, the correct statement(s) is (are) (A) Bi2O5 is more basic than N2O5 (B) NF3 is more covalent than BiF3 (C) PH3 boils at lower temperature than NH3 (D) The N–N single bond is stronger than the P–P single bond Section (B) : Group 16th 24. Amongest H2O, H2S, H2Se and H2Te the one with highest boiling point is : (A) H2O because of H-bonding. (B) H2Te because of higher molecular weight. (C) H2S because of H-bonding. (D) H2Se because of lower molecular weight. 25. The number of S–S bonds, in sulphur trioxide trimer (S3O9) is : (A) three (B) two (C) one (D) Zero Which of the following oxoacids of sulphur has –O–O– linkage ? (A) H2 S2 O3 (B) H2 S2 O5 (C) H2 S2 O6 (D) H2 S2 O8 Which of the following is not oxidised by O3 ? (A) K (B) KMnO4 (D) FeSO4 26. 27. 28. 29. 30. Which gas is evolved when PbO2 is treated with concentrated HNO3 ? (A) NO2 (B) O2 (C) N2 (D) N2O Aqueous solution of Na2S2O3 on reaction with Cl2 gives : (A) Na2S4O6 (B) NaHSO4 (C) NaCl (D) NaOH Hydrogen peroxide in its reaction with KIO4 and NH2OH respectively, is acting as a (A) reducing agent, oxidising agent (C) oxidising agent, oxidising agent 31.* (C) K2 MnO4 (B) reducing agent, reducing agent (D) oxidising agent, reducing agent The nitrogen containing compound produced in the reaction of HNO 3 with P4O10. (A) can also be prepared by reaction of P4 and HNO3 (B) is diamagnetic (C) contains one N-N bond (D) react with Na metal producing a brown gas Paragraph for Question Nos. 32 to 33 Upon heating KClO3 in the presence of catalytic amount of MnO2, a gas W is formed. Excess amount of W reacts with white phosphorus to give X. The reaction of X with pure HNO3 gives Y and Z. 32. 33. Y and Z are, respectively (A) N2O4 and HPO3 (B) N2O4 and H3PO3 (C) N2O3 and H3PO4 (D) N2O5 and HPO3 W and X are, respectively (A) O2 and P4O10 (B) O2 and P4O6 (C) O3 and P4O6 (D) O3 and P4O10 PART - II : (MAIN) / PROBLEMS (PREVIOUS YEARS) (MAIN) OFFLINE PROBLEMS 1. The number of hydrogen atom (s) attached to phosphorus atom in hypophosphorus acid is : (1) zero 2. (2) two (3) one (4) three Which of the following chemical reactions depicts the oxidizing behaviour of H 2SO4? (1) 2HI + H2SO4 → I2 + SO2 + 2H2O (3) NaCl + H2SO4 → NaHSO4 + HCl (2) Ca(OH)2 + H2SO4 → CaSO4 + 2H2O (4) 2PCl5 + H2SO4 → 2POCl3 + 2HCl + SO2Cl2 p-block elements (N & O Family) 3. Regular use of which of the following fertilizers increases the acidity of soil? (1) Superphosphate of lime (2) Ammonium sulphate (3) Potassium nitrate (4) Urea 4.* Which of the following statement is wrong? (1) The stability of hydrides increase from NH3 to BiH3 in group 15 of the periodic table : (2) Nitrogen cannot form d-p bond. (3) Single N – N bond is weaker than the single P – P bond. (4) N2O4 has two resonance structure 5. Which of the following statements regarding sulphur is incorrect ? (1) S2 molecule is paramagnetic. (2) The vapour at 200ºC consists mostly of S8 rings. (3) At 600ºC the gas mainly consists of S2 molecules. (4) The oxidation state of sulphur is never less than +4 in its compounds. 6. Which of the following is the wrong statement ? (1) ONCl and ONO– are not isoelectronic. (2) O3 molecule is bent (3) Ozone is violet-black in solid state (4) Ozone is diamagnetic gas. 7. Which of the following properties is not shown by NO ? (1) It is dimagnetic in gaseous state (3) It combines with oxygen to form nitrogen dioxide 8. (2) It is a neutral oxide (4) It's bond order is 2.5 From the following statements regarding H2O2, choose the incorrect statement : (1) It can act only as an oxidizing agent (2) It decomposed on exposure to light (3) It has to be stored in plastic or wax lined glass bottles in dark (4) It has to be kept away from dust 9. Assertion : Nitrogen and Oxygen are the main components in the atmosphere but these do not react to form oxides of nitrogen. Reason : The reaction between nitrogen and oxygen requires high temperature. (1) Both assertion and reason are correct, and the reason is the correct explanation for the assertion (2) Both assertion and reason are correct, but the reason is not the correct explanation for the assertion (3) The assertion is incorrect, but the reason is correct (4) Both are assertion and reason are incorrect 10. The pair in which phosphorous atoms have a formal oxidation state of +3 is: (1) Pyrophosphorous and hypophosphoric acids (2) Orthophosphorous and hypophosphoric acids (3) Pyrophosphorous and pyrophosphoric acids (4) Orthophosphorous and pyrophosphorous acids 11. The reaction of zinc with dilute and concentrated nitric acid, respectively, produces: (1) NO2 and NO (2) NO and N2O (3) NO2 and N2O (4) N2O and NO2 12. Hydrogen peroxide oxidises [Fe(CN)6]4– to [Fe(CN)6]3–in acidic medium but reduces [Fe(CN)6]3–to [Fe(CN)6]4– in alkaline medium. The other products formed are, respectively. (1) H2O and (H2O + O2) (2) H2O and (H2O + OH–) (3) (H2O + O2) and H2O (4) (H2O + O2) and (H2O+ OH–) 13. The compound that does not produce nitrogen gas by the thermal decomposition is : (1) NH4NO2 (2) (NH4)2SO4 (3) Ba(N3)2 (4) (NH4)2Cr2O7 p-block elements (N & O Family) (MAIN) ONLINE PROBLEMS 1. Which of the following is not formed when H2S reacts with acidic K2Cr2O7 solution ? (1) CrSO4 2. (2) Cr2(SO4)3 (3) K2SO4 (4) S Hydrogen peroxide acts both as an oxidizing and as a reducing agent depending upon the nature of the reacting species. In which of the following cases H2O2 acts as a reducing agent in acid medium ? (1) MnO4– (2) Cr2O72– (3) SO32– 3. Which of these statements is not true ? (1) NO+ is not isoelectronic with O2 (2) B is always covalent in its compounds (3) In aqueous solution, the Tl+ ion is much more stable than Tl(III) (4) LiAlH4 is a versatile reducing agent in organic synthesis. 4. The non-metal that does not exhibit positive oxidation state is: (1) Fluorine (2) Oxygen (3) Chlorine (4) KI (4) Iodine 5. Identify the incorrect statement: (1) Rhombic and monoclinic sulphur have S8 molecules. (2) S8 ring has a crown shape. (3) S2 is paramagnetic like oxygen. (4) The S–S–S bond angles in the S8 and S6 rings are the same. 6. Identify the pollutant gases largely responsible for the discoloured and Iustreless nature of marble of the Taj Mahal. (1) SO2 and NO2 (2) SO2 and O3 (3) O3 and CO2 (4) CO2 and NO2 7. In which of the following reactions, hydrogen peroxide acts as an oxidizing agent ? (1) PbS + 4H2O2  PbSO4 + 4H2O (3) l2 + H2O2 + 2OH–  2l– + 2H2O2 + O2 (2) 2MnO4– + 3H2O2  2MnO2 + 3O2 + 2H2O + 2OH– (4) HOCl + H2O2  H3O+ + Cl– + O2 8. For per gram of reactant, the maximum quantity of N2 gas is produce in which of the following thermal decomposition reactions ? (Given : Atomic wt. : Cr = 52 u, Ba = 137 u) (1) (NH4)2Cr2O7(s) → N2(g) + 4H2O(g) + Cr2O3(s) (2) 2NH4NO3(s) → 2N2(g) + 4H2O(g) + O2(g) (3) Ba(N3)2(s) → Ba(s) + 3N2(g) (4) 2NH3(g) → N2(g) + 3H2(g) 9. Good reducing nature of H3PO2 is attributed to the presence of : (1) One P–H bond (2) One P–OH bond (3) Two P–OH bonds (4) Two P–H bonds 10. The chemical nature of hydrogen peroxide is : (1) Oxidising agent in acidic medium, but not in basic medium. (2) Oxidising and reducing agent in both acidic and basic medium. (3) Reducing agent in basic medium, but not in acidic medium. (4) Oxidising and reducing agent in acidic medium, but not in basic medium. 11. Iodine reacts with concentrated HNO3 to yield Y along with other products. The oxidation state of iodine in Y, is : (1) 7 (2) 3 (3) 1 (4) 5 p-block elements (N & O Family) EXERCISE - 1 PART - I A-1. Atomic size of nitrogen is very less. Hence ‘N’ atom can approach close to another ‘N’ atom. This facilitates the lateral overlap of the p-orbitals forming -bonds. Due to large size, other atoms of the same group form only single bonds, but not multiple bonds. A-2. White phosphorus is very reactive, due to the P-P-P bond angle strain at 60º. Red phosphorus is very stable, due to chain like polymeric structure. A-3. Rhombic sulphur A-4. Phosphorite Ca3(PO4)2 and fluoroapatite Ca5(PO4)3F. B-1. Bismuth and antimony both belong to the nitrogen family and exhibit the +5 oxidation state. However, on moving down the group, i.e., from antimony to bismuth, the stability of the +5 oxidation state decreases. This is due to the inert pair effect. Thus, Bi (V) is a stronger oxidant than Sb (V). B-2. –3 to + 5, 0 B-3. Nitrogen exhibits –3 state in nitride and phosphorus exhibits –3 state in phosphide. Going down the group, the atomic size increases and metallic character also increases. Hence, the tendency to exhibit negative oxidation state decreases down the group VA. B-4. In vapour state, sulphur exists as S2 molecule. S2 molecule, like O2 molecule, has two unpaired electrons in the anti-bonding n* orbitals. Hence, like O2, it exhibits paramagnetism. B-5. (a) Oxidation state of phosphorus in P4 molecule is zero. (b) Valency of P in P4 molecule is three. Each P atom forms 3 bond pairs and possesses on lone pair. (c) Total number of P-P sigma bonds in a molecule of phosphorus is six. (d) Phosphorus-Phosphorus bond order in P4 molecule is one. (e) Bond angle 60º. (f) Tetrahedral. B-6. TeO (oxidation number of Te is +2) is basic. TeO2 (oxidation number of Te is +4) is amphoteric. TeO3 (oxidation number of Te is +6) is acidic. As the oxidation number of the element forming oxide increases, the acidic nature also increases. B-7. Tetrathionate Tetrathionate has S–S linkage. The oxidation states of sulphur are : +5, 0, 0 and +5. The average oxidation state of S is +2.5. B-8. In PH4+, phosphoros undergo sp3 hybridization, but in PH3 phosphoros uses pure p-orbitals for bonding. Hence bond angle in PH3 is nearly 90º. B-9. B-10. Oxide N2O3 Oxyacids HNO2 NO2/N2O HNO2 + HNO3 N2O5 HNO3 P4O6 H3PO3 P4O10 H3PO4 Although each of the above has same electronic distribution in bonding orbitals, nitrogen is inert because of non-polar nature of bond and high NN dissociation energy. Rest all (CO, CN–, NO+) are polar. p-block elements (N & O Family) B-11. Due to the decrease in bond (E – H) dissociation enthalpy down the group acidic character increases. C-1. Barium azide on heating undergoes thermal decomposition. Pure dinitrogen gas is obtained on heating heat → Ba + 3N2 azide. Ba(N3)2 ⎯⎯⎯ C-2. All the elements show no reaction with water. C-3. White phosphorus (P4). D-1. Due to high electronegativity of O, the O–H in H2O forms strong intermolecular H-Bonds. As a result water exists as an associated molecule while other hydrides of group 16 do not form H–Bonds and hence exist as discrete molecules. As a result, water shows unusual physical properties, i.e. high b.p., high thermal stability and weaker acidic character as compared to other hydrides of group 16. D-2. They resemble since the three ions are of comparable radii and same charge : NH4+ = 1.48 Å, K+ = 1.33 Å, Rb+ = 1.48 Å. D-3. (a) NH3 + H2O NH3.H2O (Ammonium hydroxide) NH4+ (aq) + OH– (aq) This reaction occurs to small extent only (1-2 %). Rest of NH3 remains unreacted. (b) NH3 (aq.) + HCl (aq.) NH4Cl(aq.) (c) NH3(aq.) + H2O + CO2 (aq.) ⎯→ NH4HCO3 (solvay ammonia process) D-4. Mercuric phosphide is formed by the reaction between phosphine and mercuric salt, 2PH3 + 3HgCl2 ⎯→ Hg3P2  + 6HCl D-5. N–H bond is more polar than P–H bond. Hence, NH3 forms hydrogen bonds with H2O molecules and hence dissolves in it whereas PH3 does not dissolve and forms bubbles. Also same electronegativity of P and H. D-6. NH3 + NaOCl ⎯→ NH2Cl + NaOH (fast) NH3 + NH2Cl ⎯→ NH2NH2 + NH4Cl (slow) D-7. ‘N’ atom of NH3 or ‘P’ atom of PH3 has a lone pair of electrons available for donation. Hence NH 3 and PH3 are Lewis bases. The electron pair density on a larger ‘P’ atom is less than that of smaller ‘N’ atom. Hence PH3 is a weaker base. E-1. Pure oxygen will oxidise P4O6 to P4O10 despite an excess of P4 is kept at the start of the reaction. Hence, nitrogen gas is used as a diluent. E-2. P4O10 E-3. P4O6 N2O3 E-4. F-1. ; P4O10 ; N2O5: NO2 being odd molecule, on dimerisation is converted to stable N 2O4 molecule with even number of electrons. SO3 reacts with water to form H2SO4 which forms a mist that is difficult to condense. It escapes in the atmosphere. It is, therefore, absorbed in conc. H2SO4 to form oleum which may be diluted to form H2SO4. p-block elements (N & O Family) F-2. SO2Cl2 is formed from H2SO4 by treating with excess of phosphorus pentachloride. H2SO4 + 2PCl5 ⎯→ SO2Cl2 + 2HCl + 2POCl3 SO3 is obtained from sulphuric acid by dehydration with phosphorus pentachloride. 2H2SO4 + P4O10 ⎯→ 4HPO3 + 2SO3 SO2 is obtained from conc. H2SO4, when heated with copper metal. 2H2SO4 (conc.) + Cu ⎯→ CUSO4 + 2H2O + 2SO2 F-3. SO2 G-1. Phosphorus exhibits pentavalency in excited state. Fluorine, chlorine or bromine is more electronegative and influences excitation to form PX 5. However, hydrogen is not that much electronegative to incluence the excitation in phosphorus. Hence PH 5 is not formed. G-2. PCl5 G-3. H2S G-4.  → PCl3 + Cl2 (A) PCl5 ⎯⎯ (B) PCl5 + D2O ⎯→ POCl3 + 2 DCl POCl3 + 3D2O ⎯→ D3PO4 + 3DCl G-5. PCl3 hydrolyses in the presence of moisture giving fumes of HCl PCl3 + H2O ⎯→ H3PO3 + 3 HCl G-6. (i) P4O10 + 6PCl5 ⎯→ 10POCl3 H-1. X = I2 Y = Na2S4O6 H-2. AgBr + 2Na2S2O3 Na3[Ag(S2O3)2] + NaBr H2SO4 (dil) + Na2S2O3 ⎯→ Na2SO4 + S (white turbidity) + H2O + SO2 3H2SO4 (conc.) + Na2S2O3 ⎯→Na2SO4 + 4SO2 + 3H2O H-3. Atomic number of A = 16. It is sulphur. Atomic number of B = 17. It is chlorine. Excess sulphur reacts with chlorine to give dimeric monochloride. Sulphur reacts with excess chlorine to give tetrachloride. Molten dimeric monochloride on saturation with chlorine gives dichloride. 2S + Cl2 ⎯→ S2Cl2 ; S2Cl2 + Cl2 ⎯→ 2SCl2 (ii) NH3 + NaOCl ⎯⎯→ NH2Cl + NaOH (fast) NH3 + NH2Cl ⎯⎯→ NH2NH2 + NH4Cl (slow) PART - II A-1. B-3. B-8. C-3. D-2. E-1. E-6. F-3. G-3. H-2. (D) (D) (C) (D) (C) (D) (D) (A) (B) (C) A-2. B-4. B-9. C-4. D-3. E-2. E-7. F-4. G-4. H-3. (D) (A) (B) (D) (B) (C) (D) (B) (B) (B) A-3. B-5. B-10. C-6. D-4. E-3. E-8. F-5. G-5. H-4. (A) (C) (A) (B) (B) (D) (A) (D) (A) (D) B-1. B-6. C-1. C-7. D-5. E-4. F-1. G-1. G-6. H-5. (B) (C) (B) (A) (A) (D) (C) (B) (D) (B) B-2. B-7. C-2. D-1. D-6. E-5. F-2. G-2. H-1. H-6. (C) (C) (A) (B) (B) (C) (A) (B) (D) (A) PART - III 1. 2. (A - p, q, s) ; (B - p, q, r, s) ; (C - q, r, s) ; (D - p, q, r, s) (A - q, s) ; (B - q, r) ; (C - q, s) ; (D - q) EXERCISE - 2 PART - I 1. (A) 2. (D) 3. (C) 4. (C) 5. (B) 6. (D) 7. (D) 8. (C) 9. (D) 10. (D) p-block elements (N & O Family) 11. (A) 12. (C) 13. (A) 14. (B) 15. (B) 16. (B) 17. (B) 18. (D) 19. (B) 20. (A) 21. (D) 22. (A) 23. (A) 24. (C) 25. (D) 26. (A) 27. (B) 28. (D) 29. (D) 30. (B) PART - II 1. 4 5. 2. 5 (a, b, c, e, f) 3. 3 (a, d, f) 4. 5 (b,d,e,f,g) 3 (a=1, b=2, c=1, d=4) 6. 7 (SF6) 7. 8 8. 5 (i,ii,iii,vi and vii) 9. 9 (a,b,c,d,e,f,g,h and i) 10. 6 (except a,b and c) 11. 4 12. 7 13. 4 (a,b,d and h) 14. 15. 12 16. 3 17. 6 (i, iv, v, vi, vii and ix) 18. 6 (except i, iv and ix) 19. 3 (iii, viii, ix) 20. 10 21. 24 23. 3 (i,ii and iv) 24. 5 25. 4 (i, iv, v and vi) 26. 10 22. 10 (except iii, v and xiii) 32, O2 PART - III 1. (AB) 2. (ABCD) 3. (ACD) 4. (BD) 5. (AC) 6. (AB) 7. (ABCD) 8. (ACD) 9. (ABC) 10. (ABD) 11. (ABCD) 12. (ABCD) 13. (BCD) 14. (BCD) 15. (BCD) 16. (ABCD) 17. (AC) 18. (BCD) 19. (ABCD) 20. (ABCD) 21. (AD) 22. (ABC) 23. (ACD) 24. (ABD) 25. (BD) 26. (ABCD) 27. (CD) 28. (AB) 29. (ABCD) 30. (ABCD) 31. (ABCD) 32. (ABCD) PART - IV 1. (C) 2. (B) 3. (C) 4. (B) 5. (D) 6. (C) 7. (A) 8. (A) 9. (B) 10. (A) 11. (C) 12. (D) 13. (B) EXERCISE - 3 PART - I 1. (C) 2. (A) 4. In the form of elemental nitrogen it exists as a diatomic molecule (N 2). This is due to the fact that nitrogen can form p-p multiple bond (NN) because of small size of nitrogen atom. Heavier elements of this group do not able to form p-p bonds as their atomic orbitals are so large and diffuse that they cannot have effective overlapping. Further P–P single bond is stronger than N – N single bond. Hence phosphorus as tendency to under go catenation. N  N (N2) 3. (C) (P4) 5. (C) 6. (A) 10. (a) (b) 1008 g. Structure of P4O10. 7. (A) 8. (B) 9. (C) p-block elements (N & O Family) 11. (C) 12. (C) 13. 15. A → p, s ; B → q, s ; C → r, t ; D → q, t 18. (B) 19. (B) 20.* 23.* (ABC) 24. (A) 28. (B) 29. (B) 33. (A) (B) 14. (B) 16. (D) 17. 4 (ABC) 21. (A) 22.* (BC) 25. (D) 26. (D) 27. (B) 30. (A) 31.* (BD) 32. (D) 4.* (1, 4) 5. (4) 7. (1) 8. (1) 12. (1) 13. (2) PART - II (MAIN) OFFLINE PROBLEMS 1. (2) 2. 6. All statement are correct there is no answer 9. (1) 10. (1) (4) 3. 11. (2) (4) (MAIN) ONLINE PROBLEMS 1. (1) 2. (1) 3. (1) 4. (1) 5. (4) 6. (1) 7. (1) 8. (4) 9. (4) 10. (2) 11. (4)