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Question (1)

QN0031348

A student places an ice cube in a closed bowl and leaves it on a table. After some time, the ice melts completely. Which statement is correct?

(A) A new substance has formed.
(B) Ice has changed into another state of the same substance.
(C) Ice has absorbed air and changed into water.
(D) Water has been produced by a chemical reaction.

Correct Answer: B

Explanation:

Melting is a physical change in which ice changes from solid to liquid without forming a new substance.

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Question (2)

QN0031349

Four students suggest reasons for the disappearance of rainwater from a playground after a sunny day. P. Water only seeped into the soil. Q. Water only evaporated. R. Some water seeped into the soil and some evaporated. S. Water changed into ice. Who is most likely to be correct?

(A) P
(B) Q
(C) R
(D) S

Correct Answer: C

Explanation:

On open ground, part of the water seeps into the soil while the rest evaporates into the air.

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Question (3)

QN0031350

A steel plate and a cotton cloth each receive one tablespoon of water. After some time, the steel plate becomes dry while the cloth remains wet. Which is the best explanation?

(A) Water changes into milk on the steel plate.
(B) Water evaporates from the steel plate, but part of the water is absorbed by the cloth.
(C) Steel absorbs water faster than cloth.
(D) Water disappears only from metal surfaces.

Correct Answer: B

Explanation:

Steel does not absorb water, whereas cloth absorbs water into its fibres. The remaining water evaporates gradually.

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Question (4)

QN0031351

A student notices tiny water droplets on the outer surface of a glass containing ice-cold water. Which observation best proves that the droplets did not come from inside the glass?

(A) The glass feels cold.
(B) The water level inside the glass remains unchanged while droplets appear outside.
(C) Ice cubes become smaller.
(D) The glass becomes heavier because ice melts.

Correct Answer: B

Explanation:

If water were leaking out, the water level inside would decrease. Since it remains the same, the droplets are formed by condensation of water vapour from the air.

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Question (5)

QN0031352

A teacher keeps equal amounts of water under identical conditions. • Bowl A: Wide plate • Bowl B: Narrow cup Which observation is most likely after one hour?

(A) Water in Bowl A evaporates faster due to larger exposed area.
(B) Water in Bowl B evaporates faster because it is deeper.
(C) Both evaporate equally fast.
(D) Neither evaporates.

Correct Answer: A

Explanation:

Greater exposed surface area increases the rate of evaporation.

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Question (6)

QN0031353

Which arrangement will dry a wet handkerchief in the shortest time?

(A) Folded and kept in a closed cupboard.
(B) Spread out under a fan on a sunny day.
(C) Folded and kept in the shade.
(D) Rolled tightly and placed in a plastic bag.

Correct Answer: B

Explanation:

Sunlight, moving air and larger exposed surface together increase the rate of evaporation.

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Question (7)

QN0031354

A bottle containing cold water is weighed with its cap closed. After 30 minutes, tiny droplets appear on its outer surface. What is most likely to happen to the total mass measured by the balance?

(A) It decreases because water escapes.
(B) It increases because water vapour from the air condenses on the bottle.
(C) It remains exactly the same.
(D) It first increases and then becomes zero.

Correct Answer: B

Explanation:

Water vapour from the surrounding air condenses on the cold bottle, increasing the measured mass.

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Question (8)

QN0031355

Which property correctly distinguishes water vapour from liquid water?

(A) Water vapour has a fixed shape.
(B) Water vapour occupies all available space, while liquid water has a fixed volume but no fixed shape.
(C) Water vapour cannot spread.
(D) Water vapour always appears white.

Correct Answer: B

Explanation:

Gases spread throughout the available space, whereas liquids have definite volume but take the shape of their container.

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Question (9)

QN0031356

A student heats ice until it becomes water and then continues heating until steam forms. Which sequence of changes is correct?

(A) Freezing → Condensation
(B) Melting → Evaporation
(C) Condensation → Freezing
(D) Evaporation → Melting

Correct Answer: B

Explanation:

Ice first melts into water. On further heating, water evaporates to form water vapour.

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Question (10)

QN0031357

Clothes dry very slowly on a rainy day even if the temperature is not very low. What is the main reason?

(A) Rainwater becomes heavier.
(B) The air already contains a large amount of water vapour, so evaporation becomes slower.
(C) Water changes into ice.
(D) Clothes absorb sunlight.

Correct Answer: B

Explanation:

High humidity means the air already contains a lot of water vapour, reducing the rate of evaporation.

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Question (1)

A student places an ice cube in a closed bowl and leaves it on a table. After some time, the ice melts completely. Which statement is correct?

Explanation:

Link:

Question (2)

Four students suggest reasons for the disappearance of rainwater from a playground after a sunny day. P. Water only seeped into the soil. Q. Water only evaporated. R. Some water seeped into the soil and some evaporated. S. Water changed into ice. Who is most likely to be correct?

Explanation:

Link:

Question (3)

A steel plate and a cotton cloth each receive one tablespoon of water. After some time, the steel plate becomes dry while the cloth remains wet. Which is the best explanation?

Explanation:

Link:

Question (4)

A student notices tiny water droplets on the outer surface of a glass containing ice-cold water. Which observation best proves that the droplets did not come from inside the glass?

Explanation:

Link:

Question (5)

A teacher keeps equal amounts of water under identical conditions. • Bowl A: Wide plate • Bowl B: Narrow cup Which observation is most likely after one hour?

Explanation:

Link:

Question (6)

Which arrangement will dry a wet handkerchief in the shortest time?

Explanation:

Link:

Question (7)

A bottle containing cold water is weighed with its cap closed. After 30 minutes, tiny droplets appear on its outer surface. What is most likely to happen to the total mass measured by the balance?

Explanation:

Link:

Question (8)

Which property correctly distinguishes water vapour from liquid water?

Explanation:

Link:

Question (9)

A student heats ice until it becomes water and then continues heating until steam forms. Which sequence of changes is correct?

Explanation:

Link:

Question (10)

Clothes dry very slowly on a rainy day even if the temperature is not very low. What is the main reason?

Explanation:

Link:

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