Gaseous State Exercise # 2

Exercise # 2 Part # I [Multiple Correct Choice Type Questions] 1. A gas cylinder containing cooking gas can withstand a pressure of 14.9 atmosphere. The pressure guaze of cylinder indicates 12 atmosphere at 27 ºC. Due to sudden fire in the building temperature starts rising. The temperature at which cylinder will explode is : (A) 372.5 K (B) 99.5 ºC (C) 199 ºC (D) 472.5 k 2. Which of the following statements are correct ? (A) Helium diffuses at a rate 8.65 times as much as CO does. (B) Helium escapes at a rate 2.65 times as fast as CO does. (C) Helium escapes at a rate 4 times as fast as CO2 does. (D) Helium escapes at a rate 4 times as fast as SO2 does. 3. The rate of diffusion of 2 gases ‘A’ and ‘B’ are in the ratio 16: 3. If the ratio of their masses present in the mixture is 2 : 3. Then (A) The ratio of their molar masses is 16 : 1 (B) The ratio of their molar masses is 1 : 4 (C) The ratio of their moles present inside the container is 1 : 24 (D) The ratio of their moles present inside the container is 8 : 3 4. For two gases, A and B with molecular weights MA and MB, it is observed that at a certain temperature, T, the mean velocity of A is equal to the root mean square velocity of B. Thus the mean velocity of A can be made equal to the mean velocity of B, if (A) A is at temperature, T1 and B at T2 T1 > T2 (B) A is lowered to a temperature T2 < T while B is at T (C) Both A and B are raised to a higher temperature (D) Both A and B are lowered in temperature. 5. Match of following (where Urms = root mean square speed, Uav = average speed, Ump = most probable speed) List I (A) Urms / Uav (B) Uav / Ump (C) Urms / Ump (A) (A)-(iii), (B)-(ii), (C)-(i) (C) (A)-(iii), (B)-(i), (C)-(ii) 6. 7. (i) (ii) (iii) List II 1.22 1.13 1.08 (B) (A)-(i), (B)-(ii), (C)-(iii) (D) (A)-(ii), (B)-(iii), (C)-(i). N2 + 3H2  2NH3. 1 mol N2 and 4 mol H2 are taken in 15 L flask at 27°C. After complete conversion of N2 into NH3, 5 L of H2O is added. Pressure set up in the flask is : (A) 3 x 0.0821 x 300 atm 15 (B) 2 x 0.0821 x 300 atm 10 (C) 1 x 0.0821 x 300 atm 15 (D) 1 x 0.0821 x 300 atm 10 Which of the following is not the correct set of pressure and volume at constant temperature and constant moles of gas ? P (A) 1 atm (C) 0.5 atm V 200 ml 100 L P (B) 760 mm (D) 2 atm V 0.2 L 100 mL 458 GASEOUS STATE 8. At what temperature will the total KE of 0.3 mol of He be the same as the total KE of 0.40 mol of Ar at 400 K ? (A) 533 K (B) 400 K (C) 346 K (D) 300 K 9. Potassium hydroxide solutions are used to absorb CO2. How many litres of CO2 at 1.00 atm and 22ºC would be absorbed by an aqueous solution containing 15.0 g of KOH ? (Take R = 2KOH + CO2  K2CO3 + H2O (A) 3.24 L (B) 1.62 L 10. atm / K/mole) (C) 6.48 L (D) 0.324 L The volume of a gas increases by a factor of 2 while the pressure decreases by a factor of 3. Given that the number of moles is unaffected, the factor by which the temperature changes is : (A) 11. 1 12 3 2 (B) 3 × 2 (C) 2 3 (D) 1 ×3 2 If V0 is the volume of a given mass of gas at 273 K at constant pressure , then according to Charle's law , the volume at 10 ºC will be : (A) 10 V0 (B) 2 (V0 + 10) 273 (C) V0 + 10 273 (D) 283 V 273 0 12. When a gas is compressed at constant temperature : (A) the speeds of the molecules increase (B) the collisions between the molecules increase (C) the speeds of the molecules decrease (D) the collisions between the molecules decrease 13. 2 litres of moist hydrogen were collected over water at 260C at a total pressure of one atmosphere. On analysis, it was found that the quantity of H2 collected was 0.0788 mole. What is the mole fraction of H2 in the moist gas (A) 0.989 (B) 0.897 (C) 0.953 (D) 0.967 14. When CO2 under high pressure is released from a fire extinguisher, particles of solid CO2 are formed, despite the low sublimation temperature (– 77ºC) of CO2 at 1.0 atm. It is (A) the gas does work pushing back the atmosphere using KE of molecules and thus lowering the temperature (B) volume of the gas is decreased rapidly hence, temperature is lowered (C) both (A) and (B) (D) None of the above 15. If a gas is allowed to expand at constant tempeature then which of the following does not hold true : (A) the kinetic energy of the gas molecules decreases (B) the kinetic energy of the gas molecules increases (C) the kinetic energy of the gas molecules remains the same (D) Can not be predicted 16. The vander waal gas constant ‘a’ is given by (A) 17. 1 V 3 C (B) 3PC VC2 1 RTC (C) 8 P C (D) 2 2 27 R TC 64 PC Which of the following are correct statements ? (A) vander Waals constant ‘a’ is a measure of attractive force (B) van der Waals constant ‘b’ is also called co-volume or excluded volume (C) ‘b’ is expressed in L mol–1 (D) ‘a’ is expressed in atm L2 mol–2 458 18. For gaseous state at constant temperature which of the following plot is correct ? (A) PV (B) V P PV (C) P 1 V (D) PV V 19. A hypothetical gaseous element having molecular formula Mx may be changed to another gaseous allotrope having molecular formula My at 310 K. In this act volume of the gas is contracted by 12 ml to a volume of 8 ml. The simplest possible molecular formula of the two allotropes is : (A) M5 & M3 (B) M3 & M5 (C) M1 & M2 (D) M2 & M3 20. What is the total pressure exerted by the mixture of 7.0 g of N2 , 2g of hydrogen and 8.0 g of sulphur dioxide gases in a vessel of 6 L capacity that has been kept in a reservoir at 27°C? (A) 2.5 bar (B) 4.5 bar (C) 10 atm (D) 5.7 bar 21. At what temperature root mean square speed of N2 gas is equal to that of propane gas at S.T.P. conditions. (A) 173.7°C (B) 173.7 K (C) S.T.P. (D) – 40°C 22. A gaseous mixture of three gases A, B and C has a pressure of 10 atm. The total number of moles of all the gases is 10. If the partial pressure of A and B are 3.0 and 1.0 atm respectively and if C has mol. wt. of 2.0, what is the weight 23. of C in g present in the mixture ? (A) 6 (B) 8 (C) 12 (D) 3 1 mol of a gaseous aliphahatic compound CnH3nOm is completely burnt in an excess of oxygen. The contraction in volume is (assume water get condensed out) 3   1 (A) 1+ n – m  2 4   24. 1   3 (B) 1+ n – m  4 4   3   1 (C) 1 – n – m  2 4   1   3 (D) 1+ n – m  4 2   A cylinder is filled with a gaseous mixture containing equal masses of CO and N2 . The partial pressure ratio is : (A) PN2 = PCO (B) PCO = 0.875 PN2 (C) PCO = 2 PN2 (D) PCO = 1 P 2 N2 25. Helium atom is two times heavier than a hydrogen molecule at 298 k , the average kinetic energy of helium is : (A) two times that of hydrogen molecule (B) same as that of the hydrogen molecule (C) four times that of a hydrogen molecule (D) half that of a hydrogen molecule 26. Two glass bulbs A and B are connected by a very small tube having a stop cock. Bulb A has a volume of 100 cm3 and contained the gas, while bulb B was empty. On opening the stop cock, the pressure fell down to 40%. The volume of the bulb B must be : (A) 75 cm3 (B) 125 cm3 (C) 150 cm3 (D) 250 cm3 27. One mole of a gas is defined as (A) The number of molecules in one litre of gas (B) The number of molecules in one formula weight of gas (C) The number of molecules contained in 12 grams of (12 C) isotope (D) The number of molecules in 22.4 litres of a gas at S.T.P. 460 GASEOUS STATE 28. If two moles of an ideal gas at 546 K occupies a volume of 44.8 litres, the pressure must be (A) 2 atm (B) 3 atm (C) 4 atm (D) 1 atm 29. At constant pressure which of the following does not represent Charle's law ? (A) V  30. 1 T (C) V  1 T2 (D) V  d Which of the following does not shows explicitly the relationship between Boyle's law and Charles' law ? P1 T1 (A) P = T 2 2 31. (B) V  T (B) PV = K P2 V1 (C) P = V 1 2 V2 P1 T2 (D) V = P × T 1 2 1 1 RTC (C) 8 P C 2 2 27 R TC (D) 64 PC The vander waal gas constant ‘a’ is given by 1 (A) VC 3 (B) Part # II 3PC VC2 [Assertion & Reason Type Questions] Each question has 5 choices (A), (B), (C), (D) and (E) out of which only one is correct. (A) Statement-1 is true, Statement-2 is true and Statement-2 is correct explanation for Statement-1 (B) Statement-1 is true, Statement-2 is true and Statement-2 is not correct explanation for Statement-1 (C) Statement-1 is true, Statement-2 is false (D) Statement-1 is false, Statement-2 is true (E) Both Statements are false 1. Statement-1 : Pressure exerted by a mixture of gases is equal to the sum of their partial pressures. Statement-2 : Reacting gases react to form a new gas having pressure equal to the sum of both. 2. Statement-1 : CH4,CO2 has value of Z (compressibility factor) less than one at low pressure and at low temperature. Statement-2 : Z < 1 is due to repulsive forces among the molecules. 3. Statement-1 : Excluded volume or co-volume equals to (V–nb) for n moles gas. Statement-2 : Co-volume depends on the effective size of gas molecules. 4. Statement-1 : Gases like N2, O2 behave as ideal gases at high temperature and low pressure. Statement-2 : Molecular interaction diminishes at high temperature and low pressure . 5. Statement-1 : Absolute zero temperature is a theoretically possible temperature at which the volume of the gas becomes zero. Statement-2 : The total kinetic energy of the molecules is zero at this temperature. 6. Statement-1 : In a container containing gas ‘A’ at temp 400 K, some more gas A at temp. 300 K is introduced. The pressure of the system increases. Statement-2 : Increase in gaseous particles increases the number of collisions among the molecules. 7. Statement-1 : Noble gases can be liquefied. Statement-2 : Attractive forces can exist between non-polar molecules. 460 8. Statement-1 : The diffusion rate of oxygen is smaller than that of nitrogen under identical conditions. Statement-2 : Molecular mass of nitrogen is smaller than that of oxygen. 9. Statement-1 : Most probable velocity of particles of gas is the velocity possessed by maximum fraction of particles at the same temperature. Statement-2 : On collision, more and more molecules acquire higher speed at the same temperature. 10. Statement-I : Plot of P Vs. 1/V (volume) is a straight line. Statement-II : Pressure is directly proportional to volume. 11. Statement-I : Critical temperature of the gas is the temperature at which it occupies 22.4 L of volume. Statement-II : Molar volume of every gas at NTP is 22.4 L. Statement-I : Carbondioxide has greater value of root mean square velocity urms than carbon monoxide. 12. Statement-II : urms is directly proportional to molar mass. 13. Statement-I : The effusion rate of oxygen is smaller than that of nitrogen. Statement-II : Molecular size of nitrogen is smaller than that of oxygen. EXERCISE - 2 : PART # I 1. 10. 18. 27. A, B C A, B, C D 2. 11. 19. 28. B, D D D A 3. 12. 20. 29. B, D B D A,C,D 4. 13. 21. 30. B D B A,B,C 5. 14. 22. 31. A A C B, D 6. D 15. B 23. D 7. C 16. C 24. A 8. A 17. D 25. B 9. A 26. C PART # II 1. C 2. C 3. D 4. A 5. B 6. B 7. A 8. A 9. C 10. C 11. D 12. E 13. C 462