States of Matter MCQs – Gases and Liquids Class 11
States of Matter MCQs – Gases and Liquids (Class 11 Chemistry)
Course: CBSE Class 11 Chemistry – MCQs with Answers and Explanations
Section: Physical Chemistry – MCQ Titles
The following 50 Multiple Choice Questions (MCQs) are strictly based on the NCERT chapter “States of Matter: Gases and Liquids”. The questions are arranged section-wise for systematic coverage and include clear, concept-clearing explanations, making them ideal for CBSE Class 11 board exam preparation.
Section A: States of Matter and Their Characteristics
1. Which state of matter has neither fixed shape nor fixed volume?
A. Solid
B. Liquid
C. Gas
D. Plasma
Answer: C
Explanation: Gases have neither definite shape nor definite volume.
2. Liquids differ from gases mainly because liquids
A. have fixed shape
B. have strong intermolecular forces
C. have negligible intermolecular forces
D. are incompressible
Answer: B
Explanation: Liquids have moderate intermolecular forces, stronger than gases.
3. The most compressible state of matter is
A. solid
B. liquid
C. gas
D. colloid
Answer: C
Explanation: Large intermolecular spaces make gases highly compressible.
4. Which of the following has maximum intermolecular attraction?
A. Gas
B. Liquid
C. Solid
D. Vapour
Answer: C
Explanation: Solids have the strongest intermolecular forces.
Section B: Gas Laws
5. Boyle’s law relates pressure with
A. temperature
B. volume
C. mass
D. density
Answer: B
Explanation: Boyle’s law states pressure is inversely proportional to volume at constant temperature.
6. According to Boyle’s law, PV is
A. zero
B. variable
C. constant
D. maximum
Answer: C
Explanation: At constant temperature, P × V remains constant.
7. Charles’ law relates volume with
A. pressure
B. temperature
C. density
D. mass
Answer: B
Explanation: At constant pressure, volume is directly proportional to temperature.
8. The temperature used in gas laws must be
A. Celsius
B. Fahrenheit
C. Kelvin
D. any scale
Answer: C
Explanation: Absolute temperature (Kelvin) must be used.
9. Absolute zero temperature is
A. 0°C
B. −100°C
C. −273°C
D. −273 K
Answer: C
Explanation: 0 K corresponds to −273°C.
Section C: Combined Gas Law and Ideal Gas Equation
10. Combined gas law is represented as
A. P₁V₁ = P₂V₂
B. V₁/T₁ = V₂/T₂
C. P₁V₁/T₁ = P₂V₂/T₂
D. PV = constant
Answer: C
Explanation: It combines Boyle’s and Charles’ laws.
11. Ideal gas equation is
A. PV = nRT
B. PV = RT
C. P = VRT
D. V = nPRT
Answer: A
Explanation: It relates pressure, volume, temperature, and moles.
12. The value of R depends on
A. nature of gas
B. units used
C. pressure only
D. volume only
Answer: B
Explanation: R varies with the units of pressure and volume.
13. At STP, one mole of an ideal gas occupies
A. 11.2 L
B. 22.4 L
C. 24 L
D. 1 L
Answer: B
Explanation: Molar volume at STP is 22.4 L.
Section D: Dalton’s Law of Partial Pressures
14. Dalton’s law applies to
A. liquids
B. solids
C. gases
D. solutions
Answer: C
Explanation: It applies to mixtures of non-reacting gases.
15. Partial pressure of a gas is the pressure it would exert
A. alone in the same volume
B. mixed with liquids
C. at constant mass
D. at zero volume
Answer: A
Explanation: Each gas behaves independently in a mixture.
16. Total pressure of a gas mixture equals
A. average pressure
B. sum of partial pressures
C. product of pressures
D. highest pressure
Answer: B
Explanation: Dalton’s law states total pressure is additive.
Section E: Kinetic Molecular Theory of Gases
17. According to kinetic theory, gas molecules are in
A. vibrational motion
B. rotational motion
C. random motion
D. circular motion
Answer: C
Explanation: Gas molecules move randomly in all directions.
18. Average kinetic energy of gas molecules depends on
A. pressure
B. volume
C. temperature
D. mass
Answer: C
Explanation: Kinetic energy is directly proportional to absolute temperature.
19. Gas pressure is due to
A. attraction between molecules
B. collisions with container walls
C. gravitational force
D. intermolecular repulsion
Answer: B
Explanation: Pressure arises from molecular collisions.
20. Lighter gas molecules move
A. slower than heavier ones
B. faster than heavier ones
C. at same speed
D. randomly slower
Answer: B
Explanation: At same temperature, lighter molecules move faster.
Section F: Real Gases and Deviations
21. Ideal gas behaviour is best observed at
A. high pressure, low temperature
B. low pressure, high temperature
C. high pressure, high temperature
D. low pressure, low temperature
Answer: B
Explanation: Intermolecular forces become negligible.
22. Real gases deviate from ideal behaviour due to
A. zero volume of molecules
B. intermolecular forces
C. absence of collisions
D. constant pressure
Answer: B
Explanation: Real gases have attractions and finite volume.
23. Van der Waals equation corrects
A. only pressure
B. only volume
C. both pressure and volume
D. temperature
Answer: C
Explanation: It accounts for molecular volume and attraction.
24. At very high pressure, real gases show
A. ideal behaviour
B. negative deviation
C. positive deviation
D. zero deviation
Answer: C
Explanation: Molecular volume becomes significant.
Section G: Liquids and Their Properties
25. Liquids have
A. fixed shape and volume
B. fixed shape only
C. fixed volume only
D. no definite volume
Answer: C
Explanation: Liquids have definite volume but no fixed shape.
26. Viscosity of a liquid is a measure of
A. density
B. resistance to flow
C. compressibility
D. vapour pressure
Answer: B
Explanation: Viscosity indicates internal resistance to flow.
27. Surface tension is due to
A. gravitational force
B. cohesive forces
C. adhesive forces
D. thermal energy
Answer: B
Explanation: Cohesive forces pull surface molecules inward.
28. Surface tension decreases with increase in
A. pressure
B. temperature
C. volume
D. density
Answer: B
Explanation: Higher temperature weakens intermolecular forces.
29. Capillary rise occurs due to
A. gravity only
B. viscosity
C. surface tension
D. vapour pressure
Answer: C
Explanation: Surface tension causes liquid rise in narrow tubes.
Section H: Vapour Pressure and Boiling
30. Vapour pressure of a liquid depends on
A. volume of container
B. surface area
C. temperature
D. pressure applied
Answer: C
Explanation: Vapour pressure increases with temperature.
31. Boiling occurs when vapour pressure equals
A. zero
B. atmospheric pressure
C. internal pressure
D. critical pressure
Answer: B
Explanation: At boiling point, vapour pressure equals atmospheric pressure.
32. Liquids with high intermolecular forces have
A. low boiling points
B. high vapour pressure
C. high boiling points
D. low density
Answer: C
Explanation: Strong forces require more energy to boil.
Section I: Conceptual and Numerical MCQs
33. Unit of pressure in SI system is
A. atmosphere
B. bar
C. pascal
D. mm Hg
Answer: C
Explanation: Pascal (Pa) is the SI unit of pressure.
34. Which gas law explains why balloons shrink in winter?
A. Boyle’s law
B. Charles’ law
C. Avogadro’s law
D. Dalton’s law
Answer: B
Explanation: Volume decreases with temperature.
35. Density of gas increases when
A. temperature increases
B. pressure decreases
C. pressure increases
D. volume increases
Answer: C
Explanation: Higher pressure compresses gas molecules.
36. Which has maximum vapour pressure?
A. Water
B. Alcohol
C. Ether
D. Glycerol
Answer: C
Explanation: Ether has weakest intermolecular forces.
37. Critical temperature is the temperature
A. at which gas liquefies
B. above which gas cannot be liquefied
C. at boiling point
D. at melting point
Answer: B
Explanation: Beyond critical temperature, liquefaction is impossible.
38. Compressibility factor Z for ideal gas is
A. 0
B. 1
C. >1
D. <1
Answer: B
Explanation: Ideal gases have Z = 1.
39. Which gas deviates most from ideal behaviour?
A. H₂
B. He
C. CO₂
D. Ne
Answer: C
Explanation: CO₂ has strong intermolecular attractions.
40. Which property helps insects walk on water?
A. Viscosity
B. Density
C. Surface tension
D. Vapour pressure
Answer: C
Explanation: High surface tension supports insects.
Section J: NCERT-Based Conceptual MCQs
41. Real gases behave ideally when
A. pressure is high
B. temperature is low
C. both pressure and temperature are low
D. pressure is low and temperature is high
Answer: D
Explanation: Intermolecular forces become negligible.
42. SI unit of viscosity is
A. poise
B. pascal second
C. dyne second
D. newton metre
Answer: B
Explanation: Pa·s is the SI unit.
43. Which liquid has strongest hydrogen bonding?
A. Ether
B. Water
C. Alcohol
D. Benzene
Answer: B
Explanation: Extensive hydrogen bonding in water.
44. Liquids flow but solids do not because
A. solids have no attraction
B. liquids have weaker intermolecular forces
C. solids have high density
D. liquids have no volume
Answer: B
Explanation: Weaker forces allow flow.
45. Increase in temperature causes gas pressure to
A. decrease
B. remain constant
C. increase
D. become zero
Answer: C
Explanation: Kinetic energy of molecules increases.
46. Which condition favours liquefaction of gases?
A. High temperature, low pressure
B. Low temperature, high pressure
C. High temperature, high pressure
D. Low temperature, low pressure
Answer: B
Explanation: Lower kinetic energy and closer molecules help liquefaction.
47. At constant temperature, if volume is halved, pressure becomes
A. half
B. double
C. four times
D. unchanged
Answer: B
Explanation: Boyle’s law: P ∝ 1/V.
48. Which property distinguishes liquids from gases?
A. Kinetic energy
B. Compressibility
C. Motion of molecules
D. Density only
Answer: B
Explanation: Liquids are much less compressible.
49. Vapour pressure is maximum when
A. intermolecular forces are strong
B. temperature is low
C. temperature is high
D. liquid is viscous
Answer: C
Explanation: Higher temperature increases evaporation.
50. States of matter differ mainly due to difference in
A. atomic number
B. molecular mass
C. intermolecular forces
D. chemical composition
Answer: C
Explanation: Strength of intermolecular forces determines state.
✅ Completion Note
This completes a fully NCERT-aligned, CBSE-standard set of 50 MCQs on States of Matter: Gases and Liquids, ideal for concept clarity, numerical practice, and board exam preparation.