States of Matter Practice

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NEET Chemistry - Chapter 3

States of Matter Practice Tests

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Intermolecular forces
1. The weakest intermolecular attraction among noble gas atoms is:
- A. London dispersion force (Correct)
- B. Hydrogen bond
- C. Ion-dipole force
- D. Covalent bond
Explanation: Non-polar atoms interact mainly through dispersion forces.
Intermolecular forces
2. Hydrogen bonding is strongest when hydrogen is attached to:
- A. F, O, or N (Correct)
- B. Na, K, or Ca
- C. Cl only
- D. S only
Explanation: These highly electronegative atoms create strong polarity.
States
3. Matter having definite volume but no definite shape is:
- A. Liquid (Correct)
- B. Gas
- C. Solid
- D. Plasma
Explanation: Liquids take the shape of their container.
States
4. Matter having neither definite shape nor definite volume is:
- A. Gas (Correct)
- B. Solid
- C. Liquid
- D. Crystal
Explanation: Gases expand to fill the container.
Kinetic theory
5. Pressure of an ideal gas is due to:
- A. Collision of molecules with container walls (Correct)
- B. Weight of molecules only
- C. Attraction among walls
- D. Chemical reaction with vessel
Explanation: Microscopic collisions create macroscopic pressure.
Compressibility
6. Gases are highly compressible because:
- A. Intermolecular spaces are large (Correct)
- B. Molecules have zero mass
- C. They do not move
- D. Forces are always strongest
Explanation: Large empty space allows compression.
Diffusion
7. Diffusion is fastest in:
- A. Gases (Correct)
- B. Liquids
- C. Solids
- D. Crystals
Explanation: Random molecular motion is greatest in gases.
Boyle law
8. At constant temperature, when pressure becomes three times, volume becomes:
- A. One-third (Correct)
- B. Three times
- C. Unchanged
- D. Half
Explanation: Boyle's law gives inverse relation.
Charles law
9. At constant pressure, if Kelvin temperature doubles, volume becomes:
- A. Double (Correct)
- B. Half
- C. Unchanged
- D. Four times
Explanation: Volume is directly proportional to absolute temperature.
Absolute temperature
10. For gas-law calculations, temperature should be used in:
- A. Kelvin (Correct)
- B. Celsius
- C. Fahrenheit
- D. Any unit
Explanation: Gas laws require absolute temperature.
Avogadro law
11. At same T and P, volume is proportional to:
- A. Number of moles (Correct)
- B. Molar mass
- C. Density
- D. Atomic radius
Explanation: This is Avogadro's law.
Ideal gas
12. One mole of any ideal gas at STP occupies:
- A. 22.4 L (Correct)
- B. 44.8 L
- C. 11.2 L
- D. 1 L
Explanation: Standard molar volume at STP is 22.4 L.
Dalton law
13. Total pressure of a gas mixture equals:
- A. Sum of partial pressures (Correct)
- B. Product of partial pressures
- C. Difference of pressures
- D. Always 1 atm
Explanation: This is Dalton's law of partial pressures.
Mole fraction
14. Partial pressure equals total pressure multiplied by:
- A. Mole fraction (Correct)
- B. Mass fraction
- C. Molality
- D. Molarity
Explanation: $p_i = x_iP$ for ideal gas mixtures.
Kinetic energy
15. Average kinetic energy of ideal gas molecules is proportional to:
- A. Absolute temperature (Correct)
- B. Pressure only
- C. Volume only
- D. Nature of gas only
Explanation: Temperature measures average kinetic energy.
RMS speed
16. At the same temperature, the gas with lowest molar mass has:
- A. Highest rms speed (Correct)
- B. Lowest rms speed
- C. Same rms speed as all gases
- D. Zero rms speed
Explanation: RMS speed varies inversely with square root of molar mass.
Diffusion
17. A gas diffuses faster mainly because it has:
- A. Lower molar mass (Correct)
- B. Higher boiling point
- C. Stronger hydrogen bonding
- D. Higher density
Explanation: Graham's law favors lighter gases.
Critical thinking
18. A real gas behaves more ideally at low pressure because:
- A. Molecules are far apart (Correct)
- B. Molecules stop moving
- C. Attraction becomes infinite
- D. Volume of molecules increases
Explanation: Intermolecular interactions become less important.
Critical thinking
19. High temperature pushes gases toward ideal behavior because:
- A. Kinetic energy dominates attractions (Correct)
- B. Volume becomes zero
- C. Pressure always falls to zero
- D. Mass decreases
Explanation: Faster motion reduces significance of attractions.
Units
20. The SI unit of pressure is:
- A. Pascal (Correct)
- B. Atmosphere
- C. Bar
- D. Torr
Explanation: Pascal is the SI unit though other units are common.
Gas constant
21. The universal gas constant in SI units is:
- A. 8.314 J mol$^{-1}$ K$^{-1}$ (Correct)
- B. 0.0821 J mol$^{-1}$ K$^{-1}$
- C. 22.4 J mol$^{-1}$ K$^{-1}$
- D. 1.987 L mol$^{-1}$ K$^{-1}$
Explanation: This is the SI form of R.
State property
22. Which is an extensive property of a gas sample?
- A. Volume (Correct)
- B. Temperature
- C. Pressure
- D. Density
Explanation: It depends on sample size.
State property
23. Which is an intensive property?
- A. Density (Correct)
- B. Volume
- C. Mass
- D. Number of moles
Explanation: It is independent of the amount of sample.
Application
24. When gas pressure is increased in a rigid vessel, the quantity that remains constant is:
- A. Volume (Correct)
- B. Temperature always
- C. Moles always
- D. Density always
Explanation: A rigid vessel fixes the volume.
Chapter logic
25. The kinetic theory explains gas behavior primarily through:
- A. Molecular motion and collisions (Correct)
- B. Molecular color
- C. Nuclear reactions
- D. Crystal defects
Explanation: That is the core physical picture.
Liquids
26. Boiling occurs when vapour pressure of liquid becomes equal to:
- A. External pressure (Correct)
- B. Zero
- C. Critical pressure only
- D. Density
Explanation: At that point bubbles can form throughout the liquid.
Liquids
27. Vapour pressure of a liquid generally increases with:
- A. Temperature (Correct)
- B. Surface area only
- C. External pressure only
- D. Density only
Explanation: More molecules gain enough energy to escape.
Liquids
28. A liquid with stronger intermolecular forces has:
- A. Lower vapour pressure (Correct)
- B. Higher vapour pressure
- C. Same vapour pressure as all liquids
- D. No boiling point
Explanation: Fewer molecules can escape at a given temperature.
Boiling point
29. A liquid with stronger intermolecular forces usually has:
- A. Higher boiling point (Correct)
- B. Lower boiling point
- C. No change in boiling point
- D. Zero surface tension
Explanation: More energy is needed to separate molecules.
Surface tension
30. Surface tension arises because surface molecules experience:
- A. Net inward force (Correct)
- B. Net outward force
- C. No force
- D. Only gravitational force
Explanation: This makes the liquid surface behave like a stretched film.
Viscosity
31. Viscosity is a measure of a liquid's:
- A. Resistance to flow (Correct)
- B. Density only
- C. Boiling ability
- D. Electrical conductance
Explanation: Higher viscosity means slower flow.
Capillary rise
32. Water rises in a capillary because adhesive forces with glass are:
- A. Greater than cohesive forces (Correct)
- B. Less than cohesive forces
- C. Equal to gravity
- D. Zero
Explanation: This causes a concave meniscus and capillary rise.
Meniscus
33. Mercury forms a convex meniscus in glass because:
- A. Cohesive forces exceed adhesive forces (Correct)
- B. Adhesive forces exceed cohesive forces
- C. Surface tension is zero
- D. It is a gas
Explanation: Mercury prefers to stick to itself more than to glass.
Enthalpy
34. Heat required to convert 1 mol liquid to vapour at its boiling point is:
- A. Enthalpy of vaporisation (Correct)
- B. Enthalpy of fusion
- C. Sublimation energy
- D. Bond enthalpy
Explanation: It is the latent heat of liquid-to-gas conversion.
Phase change
35. Conversion of solid directly to vapour is called:
- A. Sublimation (Correct)
- B. Fusion
- C. Condensation
- D. Deposition
Explanation: This skips the liquid phase.
Phase change
36. Conversion of vapour directly to solid is called:
- A. Deposition (Correct)
- B. Fusion
- C. Melting
- D. Evaporation
Explanation: It is the reverse of sublimation.
Phase change
37. Melting point is the temperature at which solid and liquid coexist in equilibrium at a given:
- A. Pressure (Correct)
- B. Volume
- C. Density
- D. Mole fraction
Explanation: Melting point depends on pressure.
Evaporation
38. Evaporation can occur:
- A. At all temperatures (Correct)
- B. Only at boiling point
- C. Only below melting point
- D. Only in vacuum
Explanation: Surface molecules may escape even below boiling point.
Cooling effect
39. Evaporation causes cooling because:
- A. Higher-energy molecules escape first (Correct)
- B. Water absorbs light only
- C. Pressure becomes zero
- D. Density increases suddenly
Explanation: Average kinetic energy of the remaining liquid decreases.
Liquid properties
40. Among equal-sized molecules, stronger hydrogen bonding generally causes:
- A. Higher viscosity (Correct)
- B. Lower boiling point
- C. Higher vapour pressure
- D. Lower surface tension
Explanation: Stronger attractions make flow more difficult.
Critical temperature
41. Above critical temperature, a gas cannot be liquefied by pressure alone because:
- A. Distinct liquid-gas boundary disappears (Correct)
- B. Molecules lose mass
- C. Pressure becomes zero
- D. Temperature equals absolute zero
Explanation: Beyond the critical point, separate liquid and gas phases cease to exist.
Triple point
42. The triple point is the condition where:
- A. Solid, liquid, and vapour coexist (Correct)
- B. Only liquid and gas coexist
- C. Only solid and liquid coexist
- D. Only critical fluids exist
Explanation: All three phases are in equilibrium.
Phase diagram
43. The slope of solid-liquid line for water is unusual because ice is:
- A. Less dense than liquid water (Correct)
- B. More dense than water
- C. Not hydrogen bonded
- D. A gas-like solid
Explanation: So increasing pressure lowers the melting point slightly.
Boiling variation
44. At high altitude, boiling point of water decreases because external pressure is:
- A. Lower (Correct)
- B. Higher
- C. Unchanged
- D. Equal to critical pressure
Explanation: Liquid boils when vapour pressure matches the lower outside pressure.
Pressure cooker
45. Food cooks faster in a pressure cooker because:
- A. Boiling point of water becomes higher (Correct)
- B. Water freezes faster
- C. Surface tension becomes zero
- D. Evaporation stops completely
Explanation: Higher pressure permits cooking at higher temperature.
Intermolecular forces
46. Which liquid would be expected to have the highest boiling point?
- A. The one with strongest intermolecular forces (Correct)
- B. The one with lowest molar mass always
- C. The one with brightest color
- D. The one with lowest density always
Explanation: Boiling point reflects the strength of attractions.
Property relation
47. Higher vapour pressure at a given temperature implies:
- A. Lower boiling point (Correct)
- B. Higher boiling point
- C. Higher viscosity always
- D. Stronger intermolecular force
Explanation: Such a liquid reaches external pressure sooner on heating.
Latent heat
48. During boiling at constant pressure, the supplied heat is used mainly to:
- A. Overcome intermolecular forces (Correct)
- B. Raise temperature sharply
- C. Increase nuclear energy
- D. Reduce moles
Explanation: Temperature remains constant during the phase change.
Chapter logic
49. Surface tension, viscosity, and vapour pressure are all governed mainly by:
- A. Intermolecular forces (Correct)
- B. Atomic number only
- C. Proton count only
- D. Crystal symmetry only
Explanation: Those liquid properties reflect attraction strength.
Chapter logic
50. The best way to compare liquids for NEET is to connect boiling point, vapour pressure, viscosity, and surface tension through:
- A. Strength of intermolecular attraction (Correct)
- B. Mole concept
- C. Redox number
- D. Orbital spin
Explanation: That one idea unifies most liquid-state questions.
Real gases
51. A van der Waals correction 'a' accounts for:
- A. Intermolecular attraction (Correct)
- B. Finite molecular volume
- C. Temperature correction
- D. Mole fraction
Explanation: The a term corrects the observed pressure for attractions.
Real gases
52. A van der Waals correction 'b' accounts for:
- A. Finite volume of gas molecules (Correct)
- B. Intermolecular attraction
- C. Speed of molecules
- D. Critical temperature
Explanation: The b term corrects for excluded volume.
Ideal vs real
53. At very high pressure, real gases deviate because:
- A. Molecular volume becomes significant (Correct)
- B. All attractions vanish
- C. Gas becomes monatomic
- D. Temperature becomes infinite
Explanation: The particles themselves occupy non-negligible volume.
Compressibility factor
54. If Z is less than 1, it usually indicates dominant:
- A. Attractive forces (Correct)
- B. Repulsive forces
- C. Nuclear forces
- D. No deviation
Explanation: Attractions make the gas easier to compress than ideal.
Compressibility factor
55. If Z is greater than 1, it usually indicates dominant:
- A. Repulsive forces (Correct)
- B. Attractive forces
- C. No molecular size
- D. Ideal behavior
Explanation: Repulsions or excluded volume dominate.
Critical constants
56. Critical temperature is the temperature above which:
- A. A gas cannot be liquefied by pressure alone (Correct)
- B. A liquid cannot boil
- C. A solid always melts
- D. An ideal gas forms
Explanation: It marks the upper temperature for liquefaction by compression.
Liquefaction
57. Gases with stronger intermolecular attractions liquefy:
- A. More easily (Correct)
- B. Less easily
- C. Never
- D. Only at zero pressure
Explanation: Attractions assist condensation.
Boyle temperature
58. At Boyle temperature, a real gas:
- A. Shows nearly ideal behavior over a range of pressures (Correct)
- B. Has zero pressure
- C. Has maximum volume
- D. Becomes liquid
Explanation: Repulsive and attractive effects approximately balance.
Diffusion
59. Rate of diffusion is inversely proportional to square root of:
- A. Molar mass (Correct)
- B. Temperature
- C. Pressure
- D. Volume
Explanation: This is Graham's law.
Diffusion
60. Between $H_2$ and $O_2$, the faster diffusing gas is:
- A. $H_2$ (Correct)
- B. $O_2$
- C. Both same
- D. Cannot compare
Explanation: Hydrogen has much lower molar mass.
Density relation
61. At fixed P and T, gas density is directly proportional to:
- A. Molar mass (Correct)
- B. Temperature
- C. Volume
- D. Avogadro constant
Explanation: From $d=PM/RT$.
Kinetic theory
62. RMS speed is highest for:
- A. Light gases at high temperature (Correct)
- B. Heavy gases at low temperature
- C. All gases equally
- D. Liquids only
Explanation: RMS speed grows with temperature and falls with molar mass.
Mean free path
63. Mean free path increases when gas pressure:
- A. Decreases (Correct)
- B. Increases
- C. Remains same always
- D. Becomes critical
Explanation: Molecules collide less often when they are farther apart.
Collision frequency
64. Collision frequency increases with:
- A. Pressure (Correct)
- B. Mean free path
- C. Decrease in molecular speed
- D. Lower number density
Explanation: Higher number density leads to more frequent collisions.
Kinetic relation
65. At the same temperature, average kinetic energies of $N_2$ and $O_2$ are:
- A. Equal (Correct)
- B. Higher for $N_2$
- C. Higher for $O_2$
- D. Zero
Explanation: Average kinetic energy depends only on temperature.
Kinetic relation
66. At the same temperature, rms speed of $N_2$ compared with $O_2$ is:
- A. Greater (Correct)
- B. Smaller
- C. Equal
- D. Zero
Explanation: $N_2$ has lower molar mass than $O_2$.
EOS
67. van der Waals equation for n moles is:
- A. $(P+an^2/V^2)(V-nb)=nRT$ (Correct)
- B. $PV=nRT+ab$
- C. $(P-a)(V+b)=nRT$
- D. $PV=(n+a)RT$
Explanation: That is the corrected equation of state.
EOS logic
68. The pressure correction in van der Waals equation is added because observed pressure is:
- A. Lower than ideal due to attractions (Correct)
- B. Higher than ideal due to attractions
- C. Independent of attraction
- D. Always zero
Explanation: Molecules are pulled back from the wall by neighbors.
EOS logic
69. The volume correction subtracts nb because:
- A. Free volume is less than container volume (Correct)
- B. Gas molecules have no volume
- C. Pressure must be lowered
- D. Attractions reduce size
Explanation: A part of the container volume is excluded by molecular size.
Critical thinking
70. A gas with high critical temperature likely has:
- A. Stronger intermolecular attraction (Correct)
- B. Weaker attraction
- C. No molecular volume
- D. Lower molar mass always
Explanation: It can be liquefied at relatively higher temperatures.
Units
71. One atmosphere is approximately equal to:
- A. 760 torr (Correct)
- B. 76 torr
- C. 7.6 torr
- D. 7600 torr
Explanation: This is a standard conversion.
Units
72. One bar is approximately:
- A. $10^5$ Pa (Correct)
- B. $10^3$ Pa
- C. $10^6$ Pa
- D. 760 Pa
Explanation: That is the standard relation.
Application
73. For a real gas, deviation from ideality is usually least when:
- A. P is low and T is high (Correct)
- B. P is high and T is low
- C. P is high and T is high
- D. P is low and T is low
Explanation: This minimizes both attraction and volume effects.
Application
74. If a gas shows negative deviation, then its compressibility factor is:
- A. Less than 1 (Correct)
- B. Greater than 1
- C. Equal to 0
- D. Always 1
Explanation: Negative deviation means the gas is more compressible than ideal.
Chapter logic
75. Real-gas questions become simple once you ask whether attraction or excluded volume is dominating the deviation from:
- A. Ideal behavior (Correct)
- B. Neutralisation
- C. Atomic stability
- D. Orbital filling
Explanation: That comparison unlocks most interpretation problems.
Solid state basics
76. Particles in crystalline solids are arranged in:
- A. Long-range order (Correct)
- B. Completely random order
- C. Gas-like disorder
- D. Only molecular chains
Explanation: Crystals have regular repeating arrangement.
Amorphous solids
77. Glass is an example of:
- A. Amorphous solid (Correct)
- B. Crystalline solid
- C. Liquid crystal
- D. Gas
Explanation: It lacks long-range periodic order.
Crystalline solids
78. Crystalline solids have a sharp:
- A. Melting point (Correct)
- B. Boiling point only
- C. Color always
- D. Density always equal to 1
Explanation: Pure crystals melt sharply at characteristic temperatures.
Amorphous property
79. Amorphous solids soften over a range because:
- A. They lack long-range order (Correct)
- B. They are ionic
- C. They have zero intermolecular force
- D. They are always metallic
Explanation: No single well-defined melting point exists.
Unit cell
80. The smallest repeating unit of a crystal lattice is:
- A. Unit cell (Correct)
- B. Molecule
- C. Atom always
- D. Orbital
Explanation: Repetition of the unit cell builds the crystal.
Packing
81. Coordination number in simple cubic lattice is:
- A. 6 (Correct)
- B. 8
- C. 12
- D. 4
Explanation: Each atom touches six nearest neighbors.
Packing
82. Coordination number in body-centered cubic lattice is:
- A. 8 (Correct)
- B. 6
- C. 4
- D. 12
Explanation: The center atom is surrounded by eight corner atoms.
Packing
83. Coordination number in face-centered cubic lattice is:
- A. 12 (Correct)
- B. 8
- C. 6
- D. 4
Explanation: FCC or CCP has close packing with coordination number 12.
Packing fraction
84. Most efficient packing among common cubic structures is:
- A. FCC (Correct)
- B. Simple cubic
- C. Body-centered cubic
- D. All equal
Explanation: FCC has the highest packing efficiency.
Defects
85. A vacancy defect in crystal means:
- A. A lattice point is vacant (Correct)
- B. An atom occupies interstitial site only
- C. An electron leaves atom
- D. A bond angle changes
Explanation: A particle is missing from its normal position.
Defects
86. In an interstitial defect, an extra particle occupies:
- A. An interstitial site (Correct)
- B. A lattice vacancy
- C. The nucleus
- D. A gas pocket
Explanation: It sits in a normally unoccupied space.
Ionic solids
87. Ionic solids are generally:
- A. Hard and brittle (Correct)
- B. Soft and highly volatile
- C. Good conductors in solid state
- D. Made of neutral molecules only
Explanation: Strong electrostatic forces make them hard but they cleave under stress.
Ionic solids
88. Ionic solids conduct electricity in molten state because ions become:
- A. Mobile (Correct)
- B. Smaller
- C. Neutral
- D. Covalent
Explanation: Charge transport requires moving ions.
Metallic solids
89. Metallic solids conduct due to:
- A. Delocalised electrons (Correct)
- B. Hydrogen bonding
- C. Fixed ions only
- D. Polar molecules
Explanation: Free electrons enable electrical conductivity.
Molecular solids
90. Molecular solids are generally poor conductors because:
- A. They lack free ions or electrons (Correct)
- B. They have too many protons
- C. They have high density
- D. They always melt sharply
Explanation: No mobile charge carriers are available.
Bonding
91. Diamond is extremely hard because it is a:
- A. Covalent network solid (Correct)
- B. Ionic crystal
- C. Molecular solid
- D. Metallic lattice
Explanation: A giant three-dimensional covalent network gives high hardness.
Bonding
92. Graphite conducts electricity because it has:
- A. Delocalised electrons in layers (Correct)
- B. Ionic bonds
- C. Hydrogen-bonded sheets only
- D. Positive holes only
Explanation: Each carbon contributes electrons that move within layers.
Comparison
93. A substance with low melting point and poor conductivity in solid and molten state is likely:
- A. Molecular solid (Correct)
- B. Ionic solid
- C. Metallic solid
- D. Network covalent solid
Explanation: Weak intermolecular forces usually lead to low melting points.
Comparison
94. A crystal showing anisotropy is most likely:
- A. Crystalline (Correct)
- B. Amorphous
- C. Liquid only
- D. Gas
Explanation: Properties vary with direction in ordered solids.
Comparison
95. Amorphous solids are generally:
- A. Isotropic (Correct)
- B. Anisotropic
- C. Always ionic
- D. Always metallic
Explanation: Their random arrangement makes properties direction-independent.
Phase logic
96. Supercooled liquids are associated with:
- A. Amorphous solids (Correct)
- B. Ionic crystals
- C. Close packing only
- D. Ideal gases
Explanation: Amorphous solids can be viewed as supercooled liquids.
Defect logic
97. Schottky defect lowers density because:
- A. Ions are missing from lattice (Correct)
- B. Extra ions enter lattice
- C. Electrons leave the crystal
- D. Grain boundaries increase
Explanation: Loss of ions reduces mass more than volume effect.
Defect logic
98. Frenkel defect does not significantly change density because:
- A. No ions are lost from crystal (Correct)
- B. All ions escape
- C. Volume doubles
- D. Only electrons move
Explanation: An ion merely shifts from a lattice site to an interstitial site.
Chapter logic
99. Solid-state questions often reduce to identifying the dominant bonding and packing pattern because these control:
- A. Conductivity, hardness, and melting point (Correct)
- B. Only color
- C. Only isotopic abundance
- D. Only molarity
Explanation: Bonding and structure determine macroscopic properties.
Chapter logic
100. The most useful distinction in the solid part of this chapter is between:
- A. Crystalline order and amorphous disorder (Correct)
- B. Acids and bases
- C. Orbitals and orbits
- D. Moles and molarity
Explanation: That split explains melting, anisotropy, and structural behavior.
Numerical mix
101. A gas occupies 2 L at 1 atm. At constant temperature, if pressure becomes 4 atm, new volume is:
- A. 0.5 L (Correct)
- B. 8 L
- C. 2 L
- D. 1 L
Explanation: Boyle's law gives $P_1V_1=P_2V_2$.
Numerical mix
102. A gas at 300 K occupies 3 L. At constant pressure, at 600 K its volume is:
- A. 6 L (Correct)
- B. 1.5 L
- C. 3 L
- D. 9 L
Explanation: Volume is directly proportional to Kelvin temperature.
Numerical mix
103. One mole gas at 27$^\circ$C and 1 atm occupies approximately:
- A. 24.6 L (Correct)
- B. 22.4 L
- C. 30 L
- D. 2.46 L
Explanation: Using $V=nRT/P$ at 300 K gives about 24.6 L.
Numerical mix
104. Density of an ideal gas of molar mass 44 at 1 atm and 300 K is closest to:
- A. 1.79 g L$^{-1}$ (Correct)
- B. 0.44 g L$^{-1}$
- C. 3.58 g L$^{-1}$
- D. 2.46 g L$^{-1}$
Explanation: Using $d=PM/RT$ with R = 0.0821 L atm mol$^{-1}$ K$^{-1}$ gives about 1.79.
Numerical mix
105. If rate of diffusion of gas A is twice that of gas B, molar mass of A is:
- A. One-fourth of B (Correct)
- B. Half of B
- C. Twice B
- D. Four times B
Explanation: From Graham's law, $r\propto1/\sqrt{M}$.
Thermal relation
106. At constant volume, doubling Kelvin temperature makes pressure:
- A. Double (Correct)
- B. Half
- C. Quadruple
- D. Unchanged
Explanation: Gay-Lussac law applies.
Intermolecular logic
107. Among HF, HCl, HBr, and HI, the anomalously high boiling point is shown by:
- A. HF (Correct)
- B. HCl
- C. HBr
- D. HI
Explanation: Strong hydrogen bonding raises its boiling point.
Intermolecular logic
108. Between ethanol and dimethyl ether, the higher boiling point belongs to:
- A. Ethanol (Correct)
- B. Dimethyl ether
- C. Both same
- D. Cannot compare
Explanation: Ethanol forms intermolecular hydrogen bonds.
Intermolecular logic
109. Higher surface tension generally indicates:
- A. Stronger intermolecular attraction (Correct)
- B. Weaker attraction
- C. Lower boiling point
- D. Zero viscosity
Explanation: A tighter surface film results from stronger cohesive forces.
Intermolecular logic
110. A liquid with low vapour pressure is usually:
- A. Less volatile (Correct)
- B. More volatile
- C. More ideal
- D. More diffusive
Explanation: It resists escape into vapour phase.
Solid-state mix
111. A conductor that is soft and malleable is most likely a:
- A. Metallic solid (Correct)
- B. Ionic solid
- C. Molecular solid
- D. Covalent network solid
Explanation: Metallic bonding allows layers to slide without shattering.
Solid-state mix
112. A brittle solid conducting only in molten form is likely:
- A. Ionic (Correct)
- B. Metallic
- C. Molecular
- D. Covalent network
Explanation: Mobile ions appear in molten state, not in solid state.
Phase diagram
113. The point above which liquid and gas become indistinguishable is:
- A. Critical point (Correct)
- B. Triple point
- C. Boiling point
- D. Freezing point
Explanation: Beyond it there is a supercritical fluid region.
Phase diagram
114. At the triple point, degrees of freedom for a one-component system are:
- A. 0 (Correct)
- B. 1
- C. 2
- D. 3
Explanation: From phase rule, F = C - P + 2 = 1 - 3 + 2 = 0.
Gas law mix
115. A rigid sealed cylinder is heated. Which quantity definitely increases for the gas?
- A. Pressure (Correct)
- B. Volume
- C. Moles
- D. Molar mass
Explanation: In a rigid container, heating raises pressure.
Gas law mix
116. A balloon is heated in open air. Which quantity changes most directly?
- A. Volume increases (Correct)
- B. Pressure increases largely
- C. Moles double
- D. Density stays fixed
Explanation: External pressure stays roughly constant, so volume expands.
Deviation
117. Hydrogen and helium show positive deviation at ordinary conditions mainly because:
- A. Their attractions are very weak (Correct)
- B. Their molecular volume is zero
- C. They form hydrogen bonds
- D. They are not gases
Explanation: Repulsive/excluded-volume effects dominate earlier.
Deviation
118. A gas near liquefaction usually shows:
- A. Negative deviation (Correct)
- B. Positive deviation
- C. Ideal behavior
- D. Zero pressure
Explanation: Attractions become significant near condensation.
Property ranking
119. Correct trend for stronger intermolecular forces is:
- A. Higher boiling point, higher viscosity, lower vapour pressure (Correct)
- B. Lower boiling point, lower viscosity, lower vapour pressure
- C. Higher vapour pressure, lower viscosity, higher boiling point
- D. No definite relation
Explanation: These properties move together with attraction strength.
Property ranking
120. Water's unusually high boiling point is mainly due to:
- A. Hydrogen bonding (Correct)
- B. High molar mass
- C. Ionic bonding
- D. High compressibility
Explanation: Extensive intermolecular hydrogen bonding raises its boiling point.
Sublimation
121. Dry ice changes directly from solid to gas by:
- A. Sublimation (Correct)
- B. Fusion
- C. Condensation
- D. Deposition
Explanation: Solid CO$_2$ skips the liquid phase at atmospheric pressure.
Capillary
122. Capillary rise is inversely proportional to tube radius because a narrower tube:
- A. Allows the surface-tension effect to lift liquid higher (Correct)
- B. Decreases adhesive force to zero
- C. Removes gravity
- D. Makes density vanish
Explanation: The same upward force acts over a smaller cross-section.
Meniscus
123. Water shows concave meniscus in glass because:
- A. Adhesion to glass exceeds cohesion within water (Correct)
- B. Cohesion exceeds adhesion
- C. Surface tension is absent
- D. Glass repels water strongly
Explanation: The edges climb up the glass surface.
State comparison
124. The broadest distinction between gases and liquids is that liquids have:
- A. Appreciable intermolecular attraction and definite volume (Correct)
- B. No particle motion
- C. No intermolecular force
- D. No surface
Explanation: This gives liquids shape adaptability but volume retention.
Chapter integration
125. The chapter becomes manageable once you treat solids, liquids, and gases as different balances between:
- A. Particle motion and intermolecular attraction (Correct)
- B. Protons and neutrons
- C. Acids and bases
- D. Orbitals and nodes
Explanation: That balance explains their properties across the chapter.

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