Q11. Which of the following is NOT a phase transition?
a) Melting
b) Freezing
c) Boiling
d) Dissolving
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Correct Answer: d) Dissolving
Explanation: Dissolving is a process in which a solute is dispersed evenly throughout a solvent to form a solution. It is not considered a phase transition as it does not involve a change in the state of matter but rather a change in the distribution of particles within the same phase.
Q12. The particles in a gas are:
a) Tightly packed
b) Arranged in a regular pattern
c) Far apart and move freely
d) Fixed in their positions
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Correct Answer: c) Far apart and move freely
Explanation: Gas particles are characterized by their high kinetic energy and freedom of movement. They are spaced far apart and move randomly, colliding with each other and the walls of their container, which accounts for the fluidity and compressibility of gases.
Q13. Which of the following is an example of a colloid?
a) Sugar dissolved in water
b) Salt dissolved in water
c) Milk
d) Vinegar
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Correct Answer: c) Milk
Explanation: A colloid is a mixture in which particles of one substance are dispersed evenly throughout another substance. Milk is an example of a colloid, with fat globules dispersed in water. Unlike solutions, colloids do not form homogeneous mixtures.
Q14. Which of the following is NOT true about plasma?
a) It is the most common state of matter in the universe
b) It conducts electricity
c) It has a definite shape and volume
d) It is found in stars and lightning
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Correct Answer: c) It has a definite shape and volume
Explanation: Plasma does not have a definite shape or volume. It is a state of matter composed of ionized particles that carry electrical charges, making it highly conductive. Plasma is prevalent in stars, lightning, and certain man-made devices.
Q15. Which state of matter has the highest energy and least order?
a) Solid
b) Liquid
c) Gas
d) Plasma
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Correct Answer: d) Plasma
Explanation: Plasma has the highest energy and least order among the four fundamental states of matter. Its particles are ionized and highly energetic, exhibiting behaviors distinct from those of solids, liquids, and gases.
Q16. What is the name of the process in which a gas changes directly into a solid?
a) Vaporization
b) Deposition
c) Condensation
d) Sublimation
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Correct Answer: b) Deposition
Explanation: Deposition is the process in which a gas changes directly into a solid without passing through the liquid phase. It is the reverse of sublimation. Examples include the formation of frost on a cold surface or the deposition of snowflakes from water vapor in the atmosphere.
Q17. Which of the following statements about liquids is NOT true?
a) Liquids have definite volume
b) Liquids can take the shape of their container
c) Liquids have particles arranged in a regular pattern
d) Liquids flow and can be poured
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Correct Answer: c) Liquids have particles arranged in a regular pattern
Explanation: Liquids do not have particles arranged in a regular pattern like solids. Instead, while they do have a definite volume, their particles are relatively free to move past each other, allowing liquids to flow and take the shape of their container.
Q18. Which of the following is NOT an example of a chemical change?
a) Rusting of iron
b) Burning of wood
c) Melting of ice
d) Digestion of food
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Correct Answer: c) Melting of ice
Explanation: Melting of ice is a physical change as it involves a phase transition from solid to liquid without altering the chemical composition of water. Chemical changes, on the other hand, involve the formation of new substances with different chemical properties.
Q19. What is the process by which a solid changes directly into a gas without passing through the liquid phase?
a) Evaporation
b) Condensation
c) Sublimation
d) Vaporization
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Correct Answer: c) Sublimation
Explanation: Sublimation is the process in which a solid changes directly into a gas without passing through the intermediate liquid phase. Examples include the conversion of dry ice (solid carbon dioxide) into carbon dioxide gas and the sublime odor of camphor.
Q20. Which of the following statements about solids is NOT true?
a) Solids have a definite shape
b) Solids have a definite volume
c) Solids can flow and take the shape of their container
d) Solids have particles closely packed together
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Correct Answer: c) Solids can flow and take the shape of their container
Explanation: Unlike liquids, solids cannot flow and take the shape of their container. They have a fixed shape and volume due to the close packing and rigid arrangement of their particles, which maintain their structural integrity.