Gaseous State Mock Test

GASEOUS STATE MOCK TEST SECTION - I : STRAIGHT OBJECTIVE TYPE 1. If density of vapours of a substance of molar masss 18gm/mole at 1 atm pressureand 500K is 0.36 kg m–3, then value of Z for the vapours is : ( Take R = 0.082 L atm mole–1 K–1) (A) 41 50 (B) 50 41 (C) 1.1 (D) 0.9 2. The density of gaseous HF at 1.0 atm and 300 K is 3.17 g/L. Hence, HF in gaseous state is (F = 18) (A) Dimer (B) Monomer (C) Tetramer (D) Data insufficient 3. Equal amount (mass) of methane and ethane have their total translational kinetic enegy in the ratio 3 : 1 then their temperature are in the ratio. (A) 5 : 8 (B) 45 : 8 (C) 15 : 8 (D) 8 : 5 4.  nR   1 Which of the following sketches is an isobar   P  log V log V (A) (B) log T log T log V log V (C) (D) log T 5. log T For a certain gas which deviates a litlle from ideal behaviour, the values of density,  were measured at different values of pressure, P. The plot of P/ on the Y-axis versus P on the X- axis was nonlinear and had an intercept on the Y-axis,which was equal to (A) RT M (B) M RT (C) RT (D) RT V 6. A sample of water gas has a composition by volume of 50% H2, 45% CO and 5% of CO2. Calculate the volume in litre at S.T.P of water gas wwhich on treatment with excess of steam will produce 5 litre H2. THe equation for the reaction is  CO2 + H2 CO + H2O  (A) 4.263 Litre (B) 5.263 Litre (B) 6.263 Litre (D) 7.263 Litre 7. The rate of diffusion of a sample of ozonized oxygen is 0.98 times than that of oxygen find the percentage (by volume ) of ozone in the ozonised sample. (A) 7.25 (B) 8.25 (C) 10.25 (D) 15.25 478 8. Flask A of volume 10 litre containing 20 gram of H2 and flask B of volume 10 litre containing 88 gram of CO2 are connected by a connector having negligible volume. When valve of the connector iss opened what is the composition of H2 gas in the flask B after opening the valve. 88 g CO2 10 Litre 20 g 10 Litre Thermo state at 500 K (A) 10% (B) 13% Thermo state at 200 K (C) 15% (D) 20% 9. Consider the reaction 2X(g) + 3Y(g)   Z(g) Where gases X and Y are insoluble and inert to water and Z form a basic solution. In an experiment 3 mole each of X and Y are allowed to react in 15 Litre flask at 500 K.When the reaction is complete, 5L of water is added to the flask and temperature is reduced to 300 K. The pressure in the flask is (neglect aqueous tension ). (A) 1.64 atm (B) 2.46 atm (C) 4.92 atm (D) 3.28 atm 10. Three gases A, B and C are at same temperature if their r.m.s are in the ratio 1: 1 1 : then their molar masses will 2 3 be in the ratio : (A) 1 : 2 : 3 11. (D) 3 : 2 :1 np n(n  1) (B) 2np n(n  1) (C) 3np n(n  1) (D) np 2n(n  1) A mixture of two gases A and B in the mole ratio 2 : 3 is kept in a 2 litre vessel. A second 3 litre vessel has the same two gases in the mole ratio 3 : 5. Both gas mixtures have the same temperature and same total pressure. They are allowed to intermix and the final temperature and total pressure are the same as the initial values, the final volume being 5 litres. Given that the molar masses are MA and MB, what is the mean molar masses of the final mixture ? (A) 13. (C) 1: 2 : 3 There are n containers having volumes V, 2V,.........., nV. A fixed mass of a gas is filled in all the containers connected with stopcock. All containers are at same temperature if pressure of first container is P then final pressure when all stopcocks are opened is : (A) 12. (B) 3 : 2 : 1 77M A  123M B 200 (B) 123M A  77M B 200 (C) 77M A  123M B 250 (D) 123M A  77M B 250 A 2 m long tube closed at one end is lowered vertically into water until the closed end is flush with the water surface. See figure below. Calculate the water level heigtht in the tube. (Barometric pressure - 1 atm = 10 m of hydrostatic water head, Temperature = 25°C, Density of water = 1.00 g/ml. Neglect water vapour pressure). 2m h m (A) 1.01 m (B) 0.29 m (C) 1.71 m (D) 0.92 m 480 GASEOUS STATE 14. At a certain temperature for which RT = 25 lit. atm. mol-1, the density of a gas, in gm lit-1, is d = 2.00P + 0.020 P2, where P is the pressure in atmosphere. The molecular weight of the gas in gm/mol is : (A) 25 (B) 50 (C)75 (D) 100 15. A mixture of carbon monoxide and carbon dioxide is found to have a density of 1.7 g/lit at S.T.P. The mole fraction of carbon monoxide is : (A) 0.37 (B) 0.40 (C) 0.30 (D) 0.50 16. The molecular radius for a certain gas = 1.25 Å. What is a reasonable estimate of the magnitude of the van der Waals constant, b, for the gas ? (A) 0.98 × 10–2 litre /mole (B) 1.43 × 10–2 litre/mole (C) 1.97 × 10–2 litre/mole (D) 3.33 × 10–2 litre/mole 17. Given the value of their van der Waals’ constant ‘a’ arrange the following gases in the order of their expected liquification pressure at a temperature T. T is below the critical point of all the gases. Gas CH4 Kr N2 Cl2 ‘a’(atmL2mol-1) 2.283 2.439 1.408 6.579 (A) CH4 < Kr < N2 < Cl2 (B) N2 < CH4 < Kr < Cl2 (B) Cl2 < Kr < CH4 < N2 (D) Cl2 < N2 < Kr < CH4 18. The critical volume of a gas is 0.072 lit. mol-1. The radius of the molecule will be, in cm 1  3 3 (A)   10 23  4    1  4 3 (B)   10 23  3   1  3 3 (C)  1023  4   1  3 3 (D)   10 8  4    19. Which of the following statements is not true ? (A) The ratio of the mean speed to the rms speed is independent of the temperature. (B) The square of the mean speed of the molecules is equal to the mean squared speed at a certain temperature. (C) Mean kinetic energy of the gas molecules at any given temperature is independent of the mean speed. (D) The difference between rms speed and mean speed at any given temperature for different gases diminishes as larger if larger molar masses are considerd. 20. A capillary tube of uniform diameter contains gas samples A and B, separated by a short column of Hg, ‘’ mm in length. The ends are sealed. In horizontal position, the confined gases occupy ‘a’ mm and ‘b’ mm in length with a common unknown pressure (P). In vertical position, the lengths become respectively a' mm and b' mm. Then P is equal to l b (A)   a   b' a '  l a (B)   b   a ' b'  a b (C) l     a ' b'  b a (D) l     b' a '  SECTION - II : MULTIPLE CORRECT ANSWER TYPE 21. 22. Following graph is constructed foe the fixed amount of gas. (A) From 1-2 pressure will increase. (B) From 2-3 pressure remains constant (C) Gas pressure at (3) is greater at state (1) (D) From 1-2 pressure will decrease 1 3 V 2 T Which of the following statements are correct (A) Average velocity of molecules of a gas in a container is zero. (B) All molecules in a gas are moving with the same speed. (C) If an open container is heated from 300 K to 400 K the percentage of air which goes out with respect to originally present is 25%. (D) If compressibility factor of a gas at STP is less than unity then its molar volume is less than 222.4 L at STP. 23. There are three closed containers in which equal amounts of the gas are filled. R=10cm 10cm 10cm 10 cm (I) (II) (III) If the containers are placed at the same temperatures the find the correct options : (A) Pressure of the gas is minimum in (III) container (B) Pressure of the gas is equal in (I) and (II) container (C) Pressure of the gas is maximum in (I) (D) The ratio of pressure in II and III container is 3 : 4 V 24. B A T With reference to the above graph, shoose the correct alternatives (A) PB > PA (B) PA > PB (C) Pressure first increases then decreases (D) Pressure first decreases then increases. SECTION - III : ASSERTION AND REASON TYPE 25. Statement - 1 : The value of vander waal’s constant (A) is larger for ammonia than for nitrogen. Statement - 2 : Hydrogen bonding is present in ammonia. (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 a correct explanation for statement - 1. (C) Statement - 1 is True, Statement - 2 is False (D) Statement - 1 is False, Statement - 2 is True. 26. Statement - 1 : At Boyle’s temperature a real gas behaves as ideal gas for wide range of temperature and pressure. Statement - 2 : At Boyle’s temperature vander waal constant ‘a’ and ‘b’ componsate each other. (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 a correct explana tion for statement - 1. (C) Statement - 1 is True, Statement - 2 is False (D) Statement - 1 is False, Statement - 2 is True GASEOUS STATE 27. Statement - 1 : Greater is critical temperature more easily a gas can be liquified. Statement -2 : Critical temperature depends on the magnitude of intermolecular forces of attraction between the gases. (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 a correct explana tion for statement - 1. (C) Statement - 1 is True, Statement - 2 is False (D) Statement - 1 is False, Statement - 2 is True SECTION - IV : COMPREHENSION TYPE Read the following comprehensions carefully and answer the questions. Comprehension # 1 MEASUREMENT OF PRESSURE Barometer A barometer is an instrument that is used for the measurement of pressure. The construction of the barometer is as follows Perfect Vaccum Hg is filled upto brim Thin nairow glass tube Hg P0 P0 P0= Patm P0 Cross sectional view of the capillary column A thin narrow calibrated capillary tube is filled to the brim, with a liquid such as mercury, and is inverted into a trough filled with the same fluid. Now depending on the external atmospheric pressure, the level of the mercury inside the tube will adjust itself, the reading of which can be monitored. When the mercury column inside the capillary comes to rest, then the net forces on the column should be balanced. Applying force balance, we get, Patm × A= m×g (‘A’ is the cross-sectional area of the capillary tube) If ‘’ is the density of the fluid, then m= × g × h (‘h’ is the height to which mercury has risen in the capillary) hence, Patm × A = (× g × h) × A or, Patm = gh Faulty Barometer An ideal barometer will show a correct reading only if the space above the mercury column is vacuum, but in case if some gas column is trapped in the space above the mercury column, then the barometer is classified as a faulty barometer. The reading of such a barometer will be less than the true pressure. For such a faulty barometer P ×A gas or P0A = mg + Pgas A P0 = gh + Pgas gh = P0 – Pgas Patm × A mg 28. A tube closed at one end is dipped in mercury as shown in figure-3 such that the closed surface coincides with the mercury level in the container. By how much length of the tube should be extended such that the level of Hg in the tube is 5 cm below the mercury level inside the container. (assume temperature remains constant) P = 70 cm of Hg (A) 18 cm (B) 19 cm 20 cm (C) 24 cm (D) 30 cm Fig. 3 atm 29. If above tube is placed vertically with the open end upward then the length of the air column will be (assume temperature 24 cm Patm = 75 cm remains constant) (A) 20 cm 30. 10cm 10cm, of Hg (B) 36 cm (C) 18 cm = 20.4 gm/ml (D) 15 cm A gas column is trapped between closed end of a tube and a mercury column of length (h) when this tube is placed with its open end upwards the length of gas column is (1) the length of gas column becomes (2) when open end of tube is held downwards (as shown in fig.-4). Find atmospheric pressure in terms of height of Hg column. (assume temperature remains constant) Fig.-4 h (1  2 ) (A) (   ) 2 1 h (2  1 ) (B) (   ) 1 2 (1  2 ) (C) h (   ) 2 1 (D) (h11 + h22) SECTION - V : MATRIX - MATCH TYPE 31. For a fixed amount of the gas match the two column : Column - I (A) PV Column - II (V3,T3) (V2, T2) (V1, T1) (p) T1 > T2 > T3 (P3V3) (P2V2) (P1V1) (q) P1 > P2 > P3 (P3V3) (P2V2) (P1V1) (r) V1 > V2 > V3 (d3T3) (d2T2) (d1T1) (s) d1 > d2 > d3 P (B) V T (C) P T (D) d P 484 GASEOUS STATE 32. Match the following : P B A (A) (p) Temperature is increasing V V A B (B) (q) Temperature is constant T A P (C) (r) Volume is constant B T P B (D) A (s) Pressure is increasing T 33. Match the following Column I (A) attractive tendency dominates (B) at the Boyle’s temperature in the high pressure region (C) For a gas at very low pressure and very very high temperature (D) At the critical point Column II (p) Z = 3/8 (q) Z < 1 (r) Z > 1 (s) Z = 1 SECTION - VI : SUBJECTIVE TYPE 34. A bilb of constant volume is attached to a manometer tube open at other end as shown in the figure. The manometer is filled with a liquid of density (1/3)rd that of mercury. Initially h was 228 cm. Through a small hole in the bulb gas leaked causing pressure decrease as dp  kp . If value of h is 114 cm after 7 minutes. dt Calculate value of k in units of hour–1. ( Report answer in multiple of 10–1 ) [Use : in (4/3) = 0.28 & density of Hg = 13.6 g/ml ] h GASEOUS STATE MOCK TEST 1. 10. 19. 28. B A B B 2. 11. 20. 29. C B A C 3. 12. 21. 30. D 4. A 5. A 6. B A 13. C 14. B 15. A A, B, C 22. A, C, D 23. A, C, D 24. B, C A 7. B 16. C 25. A 8. B 17. C 26. A 9. B 18. A 27. A 31. A  (p, r), B  (q, s), C  (r), D  (p, s) 32. A  (p, s), B  (p, r, s), C  (q), D  (p, r, s) 33. A  (q), B  (r), C  (s), D  (p) 486