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Question (21)

QN00981

Which substance among the following is stored in water instead of kerosene?

(A) Sodium
(B) Potassium
(C) Phosphorus
(D) Magnesium

Correct Answer: C

Explanation:

Phosphorus is stored under water.

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Question (22)

QN00982

Which of the following pairs correctly matches the substance with its storage medium?

(A) Sodium — Water
(B) Phosphorus — Kerosene
(C) Sodium — Kerosene
(D) Iron — Water

Correct Answer: C

Explanation:

Sodium is safely stored in kerosene.

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Question (23)

QN00983

A student observes that a substance bursts into flame on exposure to air. The substance is most likely:

(A) Iron
(B) Copper
(C) White phosphorus
(D) Aluminium

Correct Answer: C

Explanation:

White phosphorus ignites spontaneously in air.

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Question (24)

QN00984

Which factor mainly causes phosphorus to ignite in open air?

(A) Contact with sunlight
(B) Low density
(C) High reactivity with oxygen
(D) Contact with water

Correct Answer: C

Explanation:

Phosphorus reacts rapidly with oxygen.

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Question (25)

QN00985

Why is iron not stored under kerosene like sodium?

(A) Iron is non-metallic
(B) Iron reacts slowly with air and water
(C) Iron dissolves in kerosene
(D) Iron is colourless

Correct Answer: B

Explanation:

Iron is less reactive than sodium.

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Question (26)

QN00986

Which of the following statements best describes highly reactive substances?

(A) They do not react with air or water.
(B) They require special storage methods.
(C) They are always gases.
(D) They cannot conduct heat.

Correct Answer: B

Explanation:

Highly reactive substances need careful storage.

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Question (27)

QN00987

Sodium is generally cut using a knife because it is:

(A) Hard and brittle
(B) Soft and highly reactive
(C) Non-metallic
(D) A liquid metal

Correct Answer: B

Explanation:

Sodium is a soft metal.

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Question (28)

QN00988

The reaction of sodium with water is considered dangerous mainly because:

(A) It absorbs oxygen slowly
(B) It releases large amounts of heat
(C) It produces rust
(D) It forms acidic solutions only

Correct Answer: B

Explanation:

The reaction is highly exothermic.

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Question (29)

QN00989

Which observation indicates that phosphorus should be handled carefully?

(A) It is highly lustrous
(B) It ignites easily in air
(C) It dissolves in kerosene
(D) It is very hard

Correct Answer: B

Explanation:

Phosphorus catches fire easily in air.

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Question (30)

QN00990

Which metal is most likely to react violently if dropped into water?

(A) Gold
(B) Copper
(C) Sodium
(D) Iron

Correct Answer: C

Explanation:

Sodium reacts violently with water.

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Question (21)

Which substance among the following is stored in water instead of kerosene?

Explanation:

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Question (22)

Which of the following pairs correctly matches the substance with its storage medium?

Explanation:

Link:

Question (23)

A student observes that a substance bursts into flame on exposure to air. The substance is most likely:

Explanation:

Link:

Question (24)

Which factor mainly causes phosphorus to ignite in open air?

Explanation:

Link:

Question (25)

Why is iron not stored under kerosene like sodium?

Explanation:

Link:

Question (26)

Which of the following statements best describes highly reactive substances?

Explanation:

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Question (27)

Sodium is generally cut using a knife because it is:

Explanation:

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Question (28)

The reaction of sodium with water is considered dangerous mainly because:

Explanation:

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Question (29)

Which observation indicates that phosphorus should be handled carefully?

Explanation:

Link:

Question (30)

Which metal is most likely to react violently if dropped into water?

Explanation:

Link:

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