Test Gaseous State Questions:
1. Which of the following curves obtained at constant temperature and for a given mass of a gas is not a straight line?
(a) P – V curve (b) P - curve
(c) (d) PV – P curve
2 At constant temp. , for a given mass of an ideal gas,
(a) The ratio of pressure and volume always remains constant.
(b) Volume always remains constant.
(c) pressure always remains constant
(d) The product of the pressure and volume always remain constant.
3. A gas is initially at 1 atm pressure. To compressed it to ½ of its initial volume at constant temp. , the pressure to be applied is:
(a) 1 atm (b) 2 atm (c) ½ atm (d) 4 atm
4. The volume of a given mass of a gas at 0o centigrade is 273 L. The volume of the same gas at 10oC at constants pressure will be:
(a) (b)
(c) (d)
5. Pressure remaining constant at what temp. of the volume of the gas will be doubled of its volume at 0oC?
(a) 100oC (b) 546 oC (c) 273 K (d) 546 K
6. One litter of a gas weights 2 g at 300 K and one atm pressure. If the pressure is made 0.75 atm, at which of the following temp. will one litter of the same gas weight one gram.
(a) 450 K (b) 600 K (c) 800 K (d) 900 K
7. Which one of the following indicates the value of the gas constant R?
(a) 8.31 JK-1 mol-1 (b) 0.0821 L K-1 mol-1
(c) 1.987 JK-1 mol-1 (d) 1.987 cal K-1 mol-1
8. The average velocity of the molecules of a gas at absolute temp. T is given by
(a) (b)
(c) (d)
9. The RMS velocity of a gas at a particular temp. is 5104 cm s-1 . Its most probable velocity at the same temp. is expected to be equal to
(a) (b)
(c) (d)
10. At 27oC , the ratio of RMS velocities of ozone to oxygen is
(a) (b) (c) (d) 0.25
11. Which of the following pairs will defuse at the same rate through a porous plug?
(a) CO, N2 (b) NO2, CO2 (c) NH3, PH3 (d) NO,C2H6
12. Two separate identical bulbs contain ideal gases A and B. The density of gas A and twice that of gas B. The molecular mass of A is half that of B. If the two gases are at the same temp. , the ratio of pressure of gas A to that of gas B is:
(a) 2 (b) 1/ 2 (c) 4 (d) 1 / 4
13. 4 gram of H2 and 32 g of SO4 are presented in a gaseous mixture at N.T.P the partial pressure of H2 is
(a) equal to that of SO2 (b) Doubled that of SO2
(c) Three times that of SO2 (d) Four times that of SO2
14. The average kinetic energy per mole of an ideal gas at 27oC is
(a) 3.74 kJ (b) 36.95 kJ (c) 894.15 kJ (d) 3.741010J
15. The ratio of the average kinetic energies of hydrogen and oxygen at 50o C is:
(a) 0.5 (b) 1.0 (c) 1.5 (d) 2.0
16. The average kinetic energy of single molecule of ammonia at 0oC is :
(a) 5.6510-21kJ (b) 5.6510-19 J
(c) 5.6510-19kJ (d) 5.6510-21J
17. The root main square velocity of a gas is double when temp. is:
(a) reduced to half (b) reduced to one fourth
(c) increased four times (d) increased two times
18. Which of the following graph represented Boyle’s law?
19. A bulb containing dry ammonia and the other containing dry hydrogen chloride are connected the through a long tube. The stoppers of both the bulbs are opened simultaneously. The white fumes of ammonium chloride formed will be:
(a) Near the ammonia bulb (b) Near the hydrogen bulb
(c) At the center of the tube (d) Throughout the length of the tube.
20. The volumes of a gas X and chlorine diffusing during the same time are 35 ml and 29 ml respectively. If the molecular mass of chlorine is 71, the molecular mass of X is
(a) 35.5 (b) 48.7 (c) 12.1 (d) 142
21. An open flask contains air at 25oC. To what temp., the flask should be heated to expel one fifth of the air measured at 25oC?
(a) 49.25 oC (b) 99.5 oC (c) 125 oC (d) 200 oC
22. Which of the following statement is (are) correct?
(a) At absolute zero, the volume of an ideal gas reduced to zero.
(b) the volume of an ideal gas can never be zero.
(c) At constant volume, the pressure of a given mass of a gas is directly preoperational to its absolute temp.
(d) The zero of Kelvin scale corresponds to zero on the Celsius scale
23. The temp. at which real gas obeys the ideal gas laws over a fearly wide range of pressure is referred to as:
(a ) Boyle’s temp. (b) Charles’ temp.
(c) Critical temp. (d) inversion temp.
24. The Maxwell’s distribution of velocities in a gas is shown in the figure given below. The velocity of molecules corresponding to point X is referred to as:
(a) Average velocity (b) Most probable velocity
(c) RMS velocity (d) escape velocity
25. A gas mixture contains O2 and N2 in the ratio of 1: 4 by weight. The ratio of their number of molecules in the mixture is :
(a) 1 : 4 (b) 1 : 8 (c) 3 : 16 (d) 7 : 32
26. 20.0 g of helium is introduced in to an evacuated vessel of 5 litter capacity at 27oC. Assuming ideal behavior, predict the pressure of the gas in the container .
(a) 2.46 atm (b) 24.6 atm (c) 49.2 atm (d) 4.92 atm
27. 7.0 g of a gas occupies a volume of 4.1 L at 27oC and 1 atm pressure. The molecules mass of gas is
(a) 4.2 (b) 21 (c) 42 (d) 84
28. Which of the following are not in accordance to the kinetic theory of gasses?
(a) A gas is composed of a large number of molecules
(b) The inter molecules space in a gas is very large
(c) The collision of to molecules in involves a lose of kinetic energy.
(d) The average kinetic energy of a molecule in a gas is directly proportional to the temp. of the gas on Celsius scale.
29. Boltzmann constant (k) is given by:
(a) (b)
(c) (d)
30. Which of the Maxwell distribution curves shown in the following figure corresponds of the highest temp. of the gas.
(a) I (b) II (c) III (d) IV
31. Compressibility factor (Z) for a gas is given by:
(a) (b) (c) (d)
32. Gasses deviate from ideal behavior because there molecules:
(a) possess negligible volume (b) Are polyatomic
(c) Are not attracted to one another (d) Have forces of attraction between them.
33. A real gas most closely approaches the behavior of an ideal gas at :
(a) 15 atm and 200 K (b) 1 atm and 273 K
(c) 0.5 atm and 500 K (d) 15 atm and 500 K
34. The term that accounts for inter molecular force in van der Waal’s equation for a real gas is
(a) (b) V-b (c) RT (d) (RT)-1
35. The excluded volume per molecule in gas is
(a) equal to the actual volume of a gas molecule
(b) twice the actual volume of the gas molecule
(c) Four times the volume of the gas molecules
(d) Has no relation with the actual volume of the gas molecule
36. The values of van der Waal’s constant ‘a’ for O2 , N2, NH3 and CH4 are 1.360, 1.390, 4.170 and 2.253 L2 atm mol-2 respectively. The most easily liquefiable gas among these is :
*(a) N2 (b) NH2 (c) O2 (d) CH4
37. The compressibility factor for gas under a given set of condition is formed to be equal to 0.989. The gas under the given set of condition is:
(a) almost ideal (b) almost real
(c) highly reactive (d) least reactive
38. A closed vessel contains equal number of oxygen and hydrogen molecules at a total pressure of 740 mm.
If Oxygen if removed from the system, the pressure,
becomes half of 740 mm
becomes one third of 740 mm
becomes double of 740 mm
remains unchanged
39. Which of the following statement is (are) correct?
(a) van der Waal’s constant ‘a’ is expressed in L atm mol-2.
(b) van der Waal’s constant ‘b’ is a measured of the effective size of molecules of the gas.
(c) A gas with a higher value of ‘a’ possess a greater tendency to get liquefied.
(d) Larger the value of ‘a’ , smaller is the magnitude of van der Waal’s forces in a gas.
40. At what temp. will the total kinetic energy of 0.5 moles of He be the same as the total kinetic energy of 0.6 moles of neon at 300 K?
(a) 300 K (b) 360 K (c) 400 K (d) 250 K
41. The average kinetic energy of a gas molecules is zero at
(a) 0 oC (b) 273 oC (c) -273 oC (d) OK
42. Three molecules of a gas have velocities 100ms-1, 200 ms-1 and 300 ms-1. The RMS velocities is :
(a) 190 ms -1 (b) 200 ms -1 (c) 216 ms -1 (d) 400 ms -1
43. Which of the following statement is false:
(a) Avogadro number = 6.021022
(b) The relationship between average velocities and RMS velocities (u) is .
(c) The average kinetic energy of an ideal gas is independent of the pressure of the gas.
(d) The root main square velocity of the gas can be calculated by the formula (3 RT/m)1/2 .
44. An ideal gas obeying kinetic gas equation
(a) can be liquefied if its temp. is more then the critical temp.
(b) can be liquefied if its temp. is less then the critical pressure.
(c) can be liquefied if its pressure. is more then the critical pressure.
(d) can not be liquefied at any value of P and T.
45. A real gas can be liquefied only when its:
(a) temp. is more then the critical temp.
(b) temp. is less then the critical temp.
(c) pressure is equal to the critical pressure.
(d) volume is equal to the critical volume.
46. For a gas :
(a) (b)
(c) (d)
47. For an unknown gas, . The gas is:
(a) Monoatomic (b) diatomic (c) triatomic (d) none of these
48. For a poly atomic gas
(a) (b)
(c) (d)
49. The densities of two gasses are in the ratio of 1 : 16. The ratio of there rates is diffusion is
(a) 16 : 1 (b) 4 : 1 (c) 1:4 (d) 1 ; 16
50. If two gages X and Y have there molecules traveling with velocities in the ratio of 3 : 1, the ratio of there molecular mass is
(a) 9 (b) 3 (c) 1 / 3 (d) 1 / 9
51. 2 g of H2 and 17 g of NH3 are placed in a 8.21 litter flask at 27 oC. The total pressure of the gas mixture is
(a) 4 atm (b) 5 atm (c) 6 atm (d) 3 atm
52. In case of hydrogen and helium, the van der Waal’s forces are
(a) weak (b) strong (c) very weak (d) very strong
53. At relatively higher pressure, van der Waal’s equation reduced to
(a) PV=RT (b) PV=RT- a /V
c) PV=RT+Pb (d) PV=RT-a /V2
54. Equal weight of ethane and hydrogen are mixed in an empty container at 0oC . The fraction of the total pressure exerted by hydrogen is
(a) 1 : 2 (b) 1: 1 (c) 1 : 16 (d) 15 : 16
55. At constant volume for a fixed number of moles of a gas, the pressure of the gas increases with the rise in temp. due to
(a) Increase in average molecules
(b) Increase in the rate of collision
(c) Increase in molecular attraction
(d) Increase in the mean free path
56. For a given mass of a gas, if pressure is reduced to half and temp. is doubled, then the volume V will become:
(a) 4 V (b) 2 V2 (c) V /4 (d) 8V
57. The ratio between the root mean square velocity of H2 at 50 K and that of O2 at 800 K is
(a) 4 (b) 2 (c) 1 (d) 1 / 4
58. The molecular velocity of two gases at the same temp. are u1 and u2 and their masses are m1 and m2 respectively. Which of the following expression is correct?
(a) (b) m1u1 = m2u2
(c) (d)
59. x ml of H2 gas effuses through a hole in a container in 5 s . The time taken for the effusion of the same volume of the gas specified below under identical condition is
(a) 10 seconds : He (b) 20 seconds : O2
(c) 25 seconds : CO (d) 55 seconds : O2
60. According to Graham’s law, at a given temp. the ratio of diffusion of gases A and B is given by
(a) (b)
(c) (d)
Where P and M are pressures and molecular weights of gasses A and B respectively).
1 a 2 d 3 b 4 a 5 d 6 a 7 a, d
8 c 9 b 10 c 11 a, d 12 c 13 d 14 a
15 b 16 d 17 c 18 b 19 b 20 b 21 b
22 a, c 23 a 24 b 25 d 26 b 27 c 28 c, d
29 b 30 d 31 c 32 d 33 c 34 a 35 c
36 b 37 a 38 a 39 b, c 40 b 41 c, d 42 c
43 a 44 d 45 b 46 a 47 d 48 c 49 b
50 d 51 c 52 c 53 c 54 d 55 a, b 56 a
57 c 58 d 59 b 60 c
Solutons:
3.
4. See Charles’ law,
5. At constant pressure, V1,/T1=V2/V2
6. At 1 atm pressure, according to the gas equation
11. Under identical conditions, the gases having the same molecular mass diffuse at the same rate.
12. The bulbs are identical. Thus, the volume of two gases is the same. Same density of gas A is twice of gas B, the mass of A would be that of B. Moreover, the molecular mass of A is half that of B. Therefore, the number of moles of A would be four times those of B. The pressure of a gas depends upon the number of moles. Hence, the ratio of the pressure of gas A to that of gas that B would be 4.
13.
(P= total pressure of the mixture)
14
15. Average kinetic energy of a gas depends only upon its temperature.
19. NH3 (mol. Mass=17) being higher than HC1(mol mass =36.5) diffuses faster. Therefore, white fumes of HC1 are formed near the HC1 bulb.
20.
21. Suppose, initial number of moles of air in the flask (n1)=n
Since pressure and volume of air in the flask are constant,
(cf.PV=nRT)
25. Suppose, mass of O2=m g. Therefore, mass of N2 =4m g.
26,27
30. The distribution curve becomes wider with increase in temperature.
37. For an ideal gas, Z=1
42.
44. An ideal gas does not posses intermolecular forces of attraction (van der Waal’s forces). Hence, it can not be liquefied at any value of P and T.
50.
51.
53. According to van der Waal’s equation
ab/V2 is a very small quantity and can be neglected. Moreover, at higher pressure, Pb >> a / V.
Hence, neglecting ab / V2 and a /V, we have
54. Suppose, w g each of C2H6 and H2 are mixed.
59.
The Gaseous State 3
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