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Question (31)

QN001071

Which example best matches the statement “A substance may change in appearance but remain the same”?

(A) Burning magnesium ribbon
(B) Formation of rust
(C) Folding an origami bird
(D) Digestion of food

Correct Answer: C

Explanation:

Folding changes only the shape of paper; no new substance is formed.

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Question (32)

QN001072

Which of the following is an analytical example of physical change?

(A) Sugar dissolved in water can be recovered by evaporation
(B) Ash can be changed back to paper
(C) Burnt food can be uncooked
(D) Rust can easily become iron again naturally

Correct Answer: A

Explanation:

Sugar can be recovered after evaporation, showing no new substance formed.

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Question (33)

QN001073

A student compared melting ice and burning paper. Which statement is correct?

(A) Both are chemical changes
(B) Both are physical changes
(C) Melting ice is physical while burning paper is chemical
(D) Burning paper is physical while melting ice is chemical

Correct Answer: C

Explanation:

Melting changes only state, while burning forms new substances.

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Question (34)

QN001074

Which observation alone is NOT enough to confirm a chemical change?

(A) Formation of a new substance
(B) Permanent change in composition
(C) Change in shape
(D) Formation of precipitate

Correct Answer: C

Explanation:

A change in shape may occur in physical changes too.

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Question (35)

QN001075

Why is making dough balls from flour considered a physical change?

(A) Dough releases gas
(B) Flour changes into another substance
(C) Only shape and texture change
(D) Heat and light are produced

Correct Answer: C

Explanation:

The substance remains the same while shape changes.

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Question (36)

QN001076

Which process from the chapter demonstrates reversibility clearly?

(A) Burning wood into ash
(B) Refreezing melted ice
(C) Making popcorn
(D) Ripening fruits

Correct Answer: B

Explanation:

Melted ice can be converted back into ice again.

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Question (37)

QN001077

Which of the following situations involves a physical change with no permanent loss of material?

(A) Tearing aluminium foil
(B) Burning cotton cloth
(C) Rusting bicycle chain
(D) Cooking chapati

Correct Answer: A

Explanation:

Tearing changes only the form of aluminium foil.

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Question (38)

QN001078

A student observed that steam formed from boiling water later became liquid water again. This demonstrates that

(A) physical changes may be reversible
(B) steam is a new substance
(C) boiling is a chemical reaction
(D) water is destroyed during heating

Correct Answer: A

Explanation:

Steam can condense back into water, showing reversibility.

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Question (39)

QN001079

Which statement is correct about physical changes and reversibility?

(A) All physical changes are irreversible
(B) All reversible changes are chemical changes
(C) Many physical changes can be reversed
(D) Reversible changes always form new substances

Correct Answer: C

Explanation:

Many physical changes can return to the original state.

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Question (40)

QN001080

A student says, “The appearance changed, but the substance remained the same.” Which example supports this statement best?

(A) Burning of wood
(B) Rusting of iron
(C) Melting and refreezing wax
(D) Digestion of food

Correct Answer: C

Explanation:

Wax remains the same substance during melting and refreezing.

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Question (31)

Which example best matches the statement “A substance may change in appearance but remain the same”?

Explanation:

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Question (32)

Which of the following is an analytical example of physical change?

Explanation:

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Question (33)

A student compared melting ice and burning paper. Which statement is correct?

Explanation:

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Question (34)

Which observation alone is NOT enough to confirm a chemical change?

Explanation:

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Question (35)

Why is making dough balls from flour considered a physical change?

Explanation:

Link:

Question (36)

Which process from the chapter demonstrates reversibility clearly?

Explanation:

Link:

Question (37)

Which of the following situations involves a physical change with no permanent loss of material?

Explanation:

Link:

Question (38)

A student observed that steam formed from boiling water later became liquid water again. This demonstrates that

Explanation:

Link:

Question (39)

Which statement is correct about physical changes and reversibility?

Explanation:

Link:

Question (40)

A student says, “The appearance changed, but the substance remained the same.” Which example supports this statement best?

Explanation:

Link:

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