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Question (11)

QN002681

Which gas in air is mainly responsible for combustion?

(A) Nitrogen
(B) Oxygen
(C) Carbon dioxide
(D) Argon

Correct Answer: B

Explanation:

Oxygen supports combustion.

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Question (12)

QN002682

When warm air touches a cool surface, water vapour changes into

(A) steam
(B) oxygen
(C) droplets of water
(D) hydrogen

Correct Answer: C

Explanation:

Water vapour condenses into liquid droplets.

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Question (13)

QN002683

Lime water turns milky due to the presence of

(A) nitrogen
(B) hydrogen
(C) oxygen
(D) carbon dioxide

Correct Answer: D

Explanation:

Carbon dioxide reacts with lime water to form calcium carbonate.

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Question (14)

QN002684

Which substance is formed when carbon dioxide reacts with calcium hydroxide?

(A) Calcium oxide
(B) Calcium carbonate
(C) Calcium chloride
(D) Calcium sulfate

Correct Answer: B

Explanation:

Calcium carbonate is formed as a white precipitate.

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Question (15)

QN002685

In the lime water activity, the white insoluble particles formed are of

(A) calcium oxide
(B) calcium hydroxide
(C) calcium carbonate
(D) carbon powder

Correct Answer: C

Explanation:

Calcium carbonate particles make the solution milky.

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Question (16)

QN002686

Dust particles present in air are considered

(A) nutrients
(B) pollutants
(C) vapours
(D) compounds

Correct Answer: B

Explanation:

Dust particles pollute the air.

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Question (17)

QN002687

Which tool is used to describe air quality?

(A) API
(B) AQI
(C) PSI
(D) WQI

Correct Answer: B

Explanation:

AQI stands for Air Quality Index.

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Question (18)

QN002688

Stainless steel is an example of

(A) element
(B) compound
(C) alloy
(D) pure substance

Correct Answer: C

Explanation:

Stainless steel is a mixture of metals.

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Question (19)

QN002689

Brass is a mixture of

(A) copper and tin
(B) iron and carbon
(C) copper and zinc
(D) iron and sulfur

Correct Answer: C

Explanation:

Brass is an alloy of copper and zinc.

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Question (20)

QN002690

Bronze mainly contains copper and

(A) zinc
(B) tin
(C) iron
(D) nickel

Correct Answer: B

Explanation:

Bronze is made from copper and tin.

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Question (11)

Which gas in air is mainly responsible for combustion?

Explanation:

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Question (12)

When warm air touches a cool surface, water vapour changes into

Explanation:

Link:

Question (13)

Lime water turns milky due to the presence of

Explanation:

Link:

Question (14)

Which substance is formed when carbon dioxide reacts with calcium hydroxide?

Explanation:

Link:

Question (15)

In the lime water activity, the white insoluble particles formed are of

Explanation:

Link:

Question (16)

Dust particles present in air are considered

Explanation:

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Question (17)

Which tool is used to describe air quality?

Explanation:

Link:

Question (18)

Stainless steel is an example of

Explanation:

Link:

Question (19)

Brass is a mixture of

Explanation:

Link:

Question (20)

Bronze mainly contains copper and

Explanation:

Link:

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