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Question (21)

QN00161

If one end of a copper wire is heated strongly, heat reaches the other end faster than in an iron wire because copper is —

(A) lighter
(B) longer
(C) a better conductor of heat
(D) a poor conductor

Correct Answer: C

Explanation:

Copper conducts heat more efficiently.

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Question (22)

QN00162

In the pin-and-wax experiment, why do the pins not fall together?

(A) Wax melts at different temperatures
(B) Pins have different masses
(C) Heat takes time to travel along the strip
(D) Candle flame changes colour

Correct Answer: C

Explanation:

Heat reaches each pin at different times.

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Question (23)

QN00163

Which of the following combinations is correctly matched?

(A) Copper — Poor conductor
(B) Wood — Good conductor
(C) Glass — Poor conductor
(D) Steel — Insulator

Correct Answer: C

Explanation:

Glass does not conduct heat easily.

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Question (24)

QN00164

A person wants to stir boiling milk safely. Which material should be preferred for the handle of the spoon?

(A) Iron
(B) Aluminium
(C) Copper
(D) Plastic

Correct Answer: D

Explanation:

Plastic is a poor conductor of heat.

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Question (25)

QN00165

Which statement about good conductors of heat is correct?

(A) They do not allow heat to pass through them
(B) They allow heat to pass through them easily
(C) They absorb all heat permanently
(D) They cool objects instantly

Correct Answer: B

Explanation:

Good conductors transfer heat easily.

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Question (26)

QN00166

A metal rod is heated at one end. Which sequence correctly represents the transfer of heat?

(A) Cold end to hot end
(B) Middle to both ends
(C) Hot end to cold end
(D) Heat remains only at heated end

Correct Answer: C

Explanation:

Heat always flows from hot to cold regions.

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Question (27)

QN00167

Which of the following objects mainly uses the principle of poor conduction of heat?

(A) Iron nail
(B) Metal pan
(C) Woollen sweater
(D) Steel rod

Correct Answer: C

Explanation:

Wool reduces heat loss.

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Question (28)

QN00168

During winter, birds often puff up their feathers because trapped air —

(A) increases cooling
(B) acts as an insulator
(C) becomes heavier
(D) removes body heat quickly

Correct Answer: B

Explanation:

Trapped air reduces heat transfer.

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Question (29)

QN00169

Which material would be most suitable for making the outer covering of a thermos flask?

(A) Copper
(B) Steel
(C) Plastic
(D) Aluminium

Correct Answer: C

Explanation:

Plastic prevents heat transfer.

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Question (30)

QN00170

A student places one end of a silver rod in hot water. The other end becomes warm after some time. This transfer of heat occurs due to —

(A) conduction
(B) convection
(C) radiation
(D) evaporation

Correct Answer: A

Explanation:

Heat travels through the rod by conduction.

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Question (21)

If one end of a copper wire is heated strongly, heat reaches the other end faster than in an iron wire because copper is —

Explanation:

Link:

Question (22)

In the pin-and-wax experiment, why do the pins not fall together?

Explanation:

Link:

Question (23)

Which of the following combinations is correctly matched?

Explanation:

Link:

Question (24)

A person wants to stir boiling milk safely. Which material should be preferred for the handle of the spoon?

Explanation:

Link:

Question (25)

Which statement about good conductors of heat is correct?

Explanation:

Link:

Question (26)

A metal rod is heated at one end. Which sequence correctly represents the transfer of heat?

Explanation:

Link:

Question (27)

Which of the following objects mainly uses the principle of poor conduction of heat?

Explanation:

Link:

Question (28)

During winter, birds often puff up their feathers because trapped air —

Explanation:

Link:

Question (29)

Which material would be most suitable for making the outer covering of a thermos flask?

Explanation:

Link:

Question (30)

A student places one end of a silver rod in hot water. The other end becomes warm after some time. This transfer of heat occurs due to —

Explanation:

Link:

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