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Question (31)

QN001231

Which of the following changes can be reversed by applying heat?

(A) Rusting iron
(B) Freezing butter
(C) Burning paper
(D) Cooking vegetables

Correct Answer: B

Explanation:

Heating frozen butter melts it again.

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Question (32)

QN001232

Which process is a permanent physical change even though no new substance forms?

(A) Melting ice
(B) Breaking a glass bottle
(C) Freezing water
(D) Dissolving sugar

Correct Answer: B

Explanation:

Broken glass cannot easily be restored.

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Question (33)

QN001233

Which example best represents a temporary change?

(A) Burning cloth
(B) Rusting gate
(C) Folding umbrella
(D) Baking cake

Correct Answer: C

Explanation:

An umbrella can be folded and unfolded repeatedly.

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Question (34)

QN001234

Which statement correctly compares reversible and irreversible changes?

(A) Both always form new substances
(B) Reversible changes can return to original form
(C) Irreversible changes are always physical
(D) Reversible changes are always chemical

Correct Answer: B

Explanation:

Reversible changes can be undone.

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Question (35)

QN001235

Which process below changes only the arrangement and not the composition of matter?

(A) Burning fuel
(B) Cooking rice
(C) Melting candle wax
(D) Rusting iron

Correct Answer: C

Explanation:

Melting changes only the physical state.

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Question (36)

QN001236

A student cuts paper into pieces. Why is this generally considered irreversible?

(A) New substances form
(B) The original paper sheet cannot be restored easily
(C) Heat is released
(D) Gas is produced

Correct Answer: B

Explanation:

The original sheet cannot be obtained back easily.

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Question (37)

QN001237

Which of the following is an irreversible chemical change?

(A) Melting wax
(B) Freezing juice
(C) Burning leaves
(D) Folding clothes

Correct Answer: C

Explanation:

Burning leaves forms ash and gases.

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Question (38)

QN001238

Which process demonstrates that not all permanent changes are chemical?

(A) Burning wood
(B) Rusting iron
(C) Breaking glass
(D) Cooking food

Correct Answer: C

Explanation:

Breaking glass is a permanent physical change.

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Question (39)

QN001239

Which situation best supports the idea that some changes are temporary?

(A) Rusting of bicycle chain
(B) Ash formation from wood
(C) Water changing into ice and back into water
(D) Digestion of food

Correct Answer: C

Explanation:

Water and ice can change back and forth reversibly.

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Question (40)

QN001240

Which of the following best explains why permanent changes are important in daily life?

(A) They always reduce temperature
(B) They help produce useful new materials and products
(C) They never involve energy changes
(D) They only occur in laboratories

Correct Answer: B

Explanation:

Permanent changes help in cooking, manufacturing, and industry.

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Question (31)

Which of the following changes can be reversed by applying heat?

Explanation:

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Question (32)

Which process is a permanent physical change even though no new substance forms?

Explanation:

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Question (33)

Which example best represents a temporary change?

Explanation:

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Question (34)

Which statement correctly compares reversible and irreversible changes?

Explanation:

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Question (35)

Which process below changes only the arrangement and not the composition of matter?

Explanation:

Link:

Question (36)

A student cuts paper into pieces. Why is this generally considered irreversible?

Explanation:

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Question (37)

Which of the following is an irreversible chemical change?

Explanation:

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Question (38)

Which process demonstrates that not all permanent changes are chemical?

Explanation:

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Question (39)

Which situation best supports the idea that some changes are temporary?

Explanation:

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Question (40)

Which of the following best explains why permanent changes are important in daily life?

Explanation:

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