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Question (21)

QN00901

Oiling iron tools helps to prevent rusting because oil:

(A) Increases moisture
(B) Removes iron
(C) Prevents contact with air and water
(D) Produces rust-resistant iron

Correct Answer: C

Explanation:

Oil forms a protective layer on iron.

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Question (22)

QN00902

Greasing is useful for preventing rusting because grease forms:

(A) A shiny layer only
(B) A protective covering
(C) A heating surface
(D) A cooling effect

Correct Answer: B

Explanation:

Grease blocks air and moisture.

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Question (23)

QN00903

Applying a protective zinc layer on iron is called:

(A) Alloy formation
(B) Corrosion
(C) Galvanisation
(D) Rust cleaning

Correct Answer: C

Explanation:

Zinc coating prevents rusting of iron.

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Question (24)

QN00904

Galvanisation protects iron mainly by:

(A) Increasing rust formation
(B) Blocking contact with moist air
(C) Heating the iron continuously
(D) Removing zinc from iron

Correct Answer: B

Explanation:

Zinc prevents exposure to air and water.

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Question (25)

QN00905

Which of the following conditions is most suitable for rusting of iron nails?

(A) Dry desert air
(B) Completely dry bottle
(C) Moist coastal environment
(D) Vacuum chamber

Correct Answer: C

Explanation:

Moisture increases rusting.

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Question (26)

QN00906

An iron gate near the seashore rusts faster mainly because the air is:

(A) Dry and cool
(B) Moist and salty
(C) Hot and dusty
(D) Free from oxygen

Correct Answer: B

Explanation:

Salty moist air accelerates rusting.

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Question (27)

QN00907

What is the main role of the stopper in bottle A during the rusting experiment?

(A) To allow moisture inside
(B) To keep the bottle airtight
(C) To heat the bottle
(D) To dissolve silica gel

Correct Answer: B

Explanation:

The stopper prevents outside moisture from entering.

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Question (28)

QN00908

Which observation proves that water alone cannot cause rusting?

(A) Nail in bottle C rusted
(B) Nail in bottle A remained shiny
(C) Nail in bottle B did not rust
(D) Silica gel absorbed moisture

Correct Answer: C

Explanation:

Bottle B had water but no air, so rusting did not occur.

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Question (29)

QN00909

Which observation proves that air alone cannot cause rusting?

(A) Nail in bottle C rusted
(B) Nail in bottle A did not rust
(C) Nail in bottle B rusted quickly
(D) Oil floated on water

Correct Answer: B

Explanation:

Bottle A had air but no water.

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Question (30)

QN00910

In the rusting activity, the iron nail in bottle C was partially dipped in water to ensure contact with:

(A) Oil and silica gel
(B) Air and water simultaneously
(C) Dry air only
(D) Water vapour only

Correct Answer: B

Explanation:

Rusting needs simultaneous contact with air and water.

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Question (21)

Oiling iron tools helps to prevent rusting because oil:

Explanation:

Link:

Question (22)

Greasing is useful for preventing rusting because grease forms:

Explanation:

Link:

Question (23)

Applying a protective zinc layer on iron is called:

Explanation:

Link:

Question (24)

Galvanisation protects iron mainly by:

Explanation:

Link:

Question (25)

Which of the following conditions is most suitable for rusting of iron nails?

Explanation:

Link:

Question (26)

An iron gate near the seashore rusts faster mainly because the air is:

Explanation:

Link:

Question (27)

What is the main role of the stopper in bottle A during the rusting experiment?

Explanation:

Link:

Question (28)

Which observation proves that water alone cannot cause rusting?

Explanation:

Link:

Question (29)

Which observation proves that air alone cannot cause rusting?

Explanation:

Link:

Question (30)

In the rusting activity, the iron nail in bottle C was partially dipped in water to ensure contact with:

Explanation:

Link:

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