Chemistry 1st Year Chapter 3 Gases Notes MCQs Bank

chemistry 11th notes chapter 3

1. The partial pressure of oxygen in air is:

 
 
 
 

2. Which of the following is not an intermolecular force between molecules:

 
 
 
 

3. Boyle’s law is represented as:

 
 
 
 

4. The highest temperature at which a substance can exist as a liquid is called its:

 
 
 
 

5. Which one of the following gases is more ideal at STP:

 
 
 
 

6. Equal masses of methane and oxygen are mixed in an empty container at 25°C. The fraction of total pressure exerted by oxygen is:

 
 
 
 

7. The densities of gases are expressed in:

 
 
 
 

8. At constant temperature the pressure of an ideal gas is doubled, its density becomes:

 
 
 
 

9. The molar volume of CO₂ is maximum at:

 
 
 
 

10. Which gas cannot be dried by passing over H₂SO₄:

 
 
 
 

11. What is the simplest form of matter:

 
 
 
 

12. One dm³ of H₂ at STP contains number of molecules:

 
 
 
 

13. Which gas deviate more from ideal behaviour at high pressure:

 
 
 
 

14. Eight grams each of O₂ and H₂ at 27°C will have total K.E in the ratio:

 
 
 
 

15. The kinetic molecular theory of gases was put forward in 1738 by:

 
 
 
 

16. Which one of the following molecules have maximum root mean square velocity at 25°C:

 
 
 
 

17. Lind’s method is employed for:

 
 
 
 

18. Which one of the following has least critical temperature:

 
 
 
 

19. Which of these gases diffuse more quickly than oxygen:

 
 
 
 

20. Which of the following gases diffuse more rapidly:

 
 
 
 

21. What will be the pressure of 1 mole of an ideal gas maintained at 300 K and 250 cm3 volume:

 
 
 
 

22. 0.5 mole of NO₂ and 0.5 mole of SO₃ gas have equal:

 
 
 
 

23. Absolute zero is equal to:

 
 
 
 

24. The equation VT = Vo(1 + t/273) is based on:

 
 
 
 

25. The spreading of fragrance in air is due to:

 
 
 
 

26. Critical temperature of a gas depends upon:

 
 
 
 

27. Hydrogen diffuses four times more rapidly than volume of an unknown gas, molar mass of unknown gas should be:

 
 
 
 

28. Under what conditions real gases deviate from ideal behaviour:

 
 
 
 

29. For a gas obeying Boyle’s law if pressure is doubled the volume becomes:

 
 
 
 

30. The weakest intermolecular force is:

 
 
 
 

31. The expression for root mean square velocity is:

 
 
 
 

32. Which pair of gases do not obey Dalton’s law of partial pressure?

 
 
 
 

33. Which one has the lowest density at room temperature:

 
 
 
 

34. The diffusion of gases at absolute zero will be:

 
 
 
 

Short Questions

1. A gas occupies 100 dm³ at 283 K.what will be its volume at -273ᵒC at constant pressure?
2. Calculate fraction of total pressure exerted by Oxygen when equal masses of CH₄ and O₂ are mixed
3. Calculate number of molecules and number of atoms in 20 cm³ of CH₄ at 0 ⁰C and 700mm. ‘
4. Calculate the density of methane at STP.
5. Calculate the S.I.unit of R?
6. Calculate the value of R in S.I units.
7. Calculate the value of R in units’ atm.dm³ .K⁻¹ mol⁻¹
8. Charles’s law is not obeyed when the temperature is measured on celsius scale.Justify it?
9. Define Plasma. Give its one application.
10. Define pressure. Give its different units.
11. Derive expression for the density of the gas using general gas equation.
12. Derive expression for the molecular mass of the gas using general gas equation.
13. Derive Graham’s law of diffusion in the light of KMT of gases.
14. Explain Boyle’s law with the help of KMT.
15. Gases deviate more from the general gas equation at 0 ᵒC and deviate to less extent at 100 ᵒC.Why?
16. Give four fundamental postulates of KMT of gases.
17. Give tw⁰Causes for deviation of gases from ideality?
18. Give two applications of Plasma.
19. Greater the temperature of the gas closer the straight line of P versus 1/vto the pressure axis.justify it?
20. H₂ and He behave ideally while Cl₂ and SO₂ do not. Why?
21. How do you explain that -273ᵒC is theoretical temperature and is not attainable?
22. How do you say that the pressure of the dry gas is equal to the difference of total pressure and aqueous tension of H₂O?
23. How is fluorescent light bulb different from ordinary light bulb?
24. How the behavior of real gases is given by van Der waal’s equation?
25. How the critical temperature is an essential criteria to be considered for the liquefaction of gases?
26. How the density of an ideal gas doubles by doubling the pressure or decreasing the temperature on Kelvin scale by ¹/²?
27. How the value of the general gas constant’R can be derived with the help of Avogadro’s law?
28. Hydrogen and helium are ideal at room temperature but SO₂ and CI₂ are non-ideal.How do you explain it?
29. In joule-Thomson effect sudden expansion of th e gas molecules needs energy.Why?
30. Joule-Thomson effect is operative in the Linde’s method of liquefaction of air.How?
31. Justify that 1 cm³ of H₂ and 1 cm³ of CH₄ at STP will have same number of molecules.When one molecule of CH₄ is 8 time heavier that of hydrogen?
32. Justify that the volume of given mass of a gas becomes theoretically zero at -273ᵒC?
33. Justify that volume of gas becomes theoretically zero at -273 C
34. Lighter gases diffuse more rapidly than heavier gases.Give reason?
35. Pressure of ammonia gas at given conditions is less as calculated by Vander Waal equation than that calculated by general gas equation. Why?
36. Pressure of NH₃ gas at given conditions is less when calculated by Van der Wall’s equation than that calculated by general gas equation.Why?
37. Prove that PA=Pt.XA
38. Rate of diffusion of ammonia is more than that of HCl. Why?
39. SO₂ is comparatively non-ideal at 273 K but behaves ideally at 327 K.Why?
40. Some of the postulates of Kinetic Molecular Theory are faulty. Justify
41. State Dalton’s law of partial pressures.Why is it necessary that no forces of attractions should be there to obey this law?
42. State Joule-Thomson Effect. Write its application.
43. The actual volume of O₂ gas at room temperature and 1 atm.Pressure is negligible as compared to volume occupied by one mole of this gas.But this actual volume is not negligible at high pressures.justify it?
44. The plot of PV versus P is a straight line at constant temperature and with a fixed number of moles of an ideal gas.Why?
45. The product of pressure and volume at constant temperature and number of moles is a constant quantity.Why?
46. Throw some light on the factor 1/273 in Charles’s law?
47. Water vaporous do not behave ideally at 273 K.Why?
48. What are application of Plasma?
49. What are characteristics of plasma?
50. What are isotherms?
51. What are isotherms?What happens to the position of isotherms when they are plotted at high temperature for a particular gas?
52. What are Neon advertisement signs?
53. What are the units of Vander Waal’s constants ‘a’ and ‘b’.
54. What are various scales of thermometer?Convert 80 ᵒC to Fahrenheit?
55. What are various unit of pressure?
56. What do you mean by absolute zero temperature of gases?
57. What do you mean by critical temperature of gases?
58. What is absolute zero?What happens to real gases while approaching it?
59. What is Avogadro’s law of gasses?
60. What is physical significance of Vander Waal’s constants ‘a’ and ‘b’.
61. What is the Physical significance of van der wall’s constants ‘a’ and ‘b’?
62. When a gas obeys the Bolye’s law the isotherms for the gas can be plotted?
63. Where do natural and artificial plasma exist?
64. Where is Plasma found?
65. Why do we get a straight line when pressures are plotted against inverse of volumes?This straight line changes its position in the graph by varying the temperature.justify it?
66. Why is the Boyle’s law applicable only to the ideal gases?
67. Why lighter gases diffuse more rapidly than heavier gases?
68. Why pilots feel uncomfortable breathing at high altitude and divers cannot use normal air?
69. Why regular air can’t be used in diver’s tanks?
70. Why some amount of pressure should be added in the measured pressure of the non-ideal gas to get the ideal pressure of gas?
71. Why the excluded volume (b) is more than volume (Vm) of the gas?
72. Why the gases deviate from ideal behavior at high pressure and low temperature?
73. Why the non-polar gases like H₂ and he have a very low critical temperatures while polar gases like NH₃ and SO₂ have critical temperatures sufficiently above room temperature?
74. Why the pressure correction is done by van der waal?
75. Why the volume correction is done by van der wall?
76. Write down the value of atmospheric pressure in four different units.
77. Write two Characteristics of plasma.

Long Questions

1. Describe Dalton’s law of partial pressures. Write its three applications.
2. State and explain Graham’s law of diffusion of gases.
3. Calculate the density of methane at STP. What happens to…
4. A sample of carbon monoxide gas occupies 150.0 mL at 25.0°C. It is then cooled at constant pressure until it occupies 100.0 mL. What is the new’ temperature?
5. What is the general gas equation? Derive it in various forms.
6. Write a note on Linde’s method of liquefaction.
7. What is kinetic molecular theory of gases? Give its postulates.
8. How pressure and volume were corrected by vander Waal?
9. Derive Boyle’s law and Charle’s law from kinetic equation of gases.
10. What is Boyle’s law of gases? Give its experimental verification.
11. What are isotherms? What happens to the positions of isotherms when they are plotted at high temperature for a particular gas.
12. Why do we get a straight line when pressures exerted on a gas are plotted against inverse of volumes? This straight line changes its position in the graph by varying the temperature. Justify it.
13. Derive van der Waal’s equation for real gases.
14. What is the physical signiicance of van der Waals’constants, ’a’ and ’b? Give their units.
15. A sample of krypton with a volume of 6.25 dm³ , a pressure of 765 torr and a temperature of 20 °C is expanded to a volume of 9.55 dm³ and a pressure of 375 torr. What will be its inal temperature in °C
16. Working at a vacuum line, a chemist isolated a gas in a weighing bulb with a volume of 255 cm³, at a temperature of 25 °C and under a pressure in the bulb of 10.0 torr. The gas weighed 12.1 mg. What is the molecular mass of this gas?
17. What pressure is exerted by a mixture of 2.00g of H and 8.00g of N at 273K in a 10 dm³ vessel?
“18. Calculate the density of CH₄ at 0⁰C and 1 atmospheric pressure, what will happen to the density if
(a) temperature is increase to 27⁰C.
(b) the pressure is increased to 2 atmospheres at 0 ⁰C.”
19. Calculate the mass of 1 dm³ of NH₃ gas at 30⁰C and 1000 mm Hg pressure, considering that NH₄ is behaving ideally.
20. Calculate the masses of 10²⁰ molecules of each of H₂ ,O₂ and CO₂ at STP. What will happen to the masses of these gases, when the temperature of these gases are increased by 100 ᵒC and pressure is decreased by 100 torr.
“21. Calculate the number of molecules and the number of atoms in the given amounts of each gas
(a) 20cm³ of cH₄ at 0 ⁰C and pressure of 700 mm of mercury
(b) 1 cm³ of NH₄ at 100 ⁰C and pressure of 1.5 atm”

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