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Question (11)

QN00891

An iron nail kept only in dry air does not rust because:

(A) Iron becomes inactive
(B) Water is absent
(C) Air is absent
(D) Sunlight is absent

Correct Answer: B

Explanation:

Water is necessary for rusting.

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Question (12)

QN00892

An iron nail dipped completely in boiled water and covered with oil does not rust because:

(A) Water prevents rusting
(B) Air is absent
(C) Oil reacts with iron
(D) Iron becomes stronger

Correct Answer: B

Explanation:

Oxygen from air cannot reach the nail.

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Question (13)

QN00893

Which statement is correct about rusting?

(A) Rusting requires only water.
(B) Rusting requires only air.
(C) Rusting requires both air and water.
(D) Rusting occurs only in sunlight.

Correct Answer: C

Explanation:

Rusting occurs in moist air.

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Question (14)

QN00894

The gradual deterioration of metal surfaces due to air, water, or other substances is called:

(A) Rusting
(B) Corrosion
(C) Distillation
(D) Crystallisation

Correct Answer: B

Explanation:

Corrosion damages metal surfaces gradually.

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Question (15)

QN00895

A green coating is commonly formed on the surface of:

(A) Iron objects
(B) Aluminium objects
(C) Copper objects
(D) Zinc objects

Correct Answer: C

Explanation:

Copper develops a green coating on exposure to air.

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Question (16)

QN00896

A black coating develops on objects made of:

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

Correct Answer: A

Explanation:

Silver tarnishes forming a black coating.

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Question (17)

QN00897

Which of the following is an example of corrosion?

(A) Melting of wax
(B) Burning of wood
(C) Green coating on copper
(D) Dissolving sugar in water

Correct Answer: C

Explanation:

Corrosion includes formation of coatings on metals.

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Question (18)

QN00898

Rusting is considered a serious problem because it:

(A) Makes iron lighter
(B) Damages iron structures
(C) Produces electricity
(D) Removes paint from walls

Correct Answer: B

Explanation:

Rust weakens iron structures.

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Question (19)

QN00899

Large amounts of money are spent every year mainly to:

(A) Decorate iron objects
(B) Repair or replace rusted iron structures
(C) Manufacture gold objects
(D) Produce silica gel

Correct Answer: B

Explanation:

Rusting causes major economic loss.

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Question (20)

QN00900

Which method can prevent rusting of iron?

(A) Keeping iron in moist air
(B) Washing iron with water daily
(C) Painting the iron surface
(D) Scratching the iron surface

Correct Answer: C

Explanation:

Paint prevents contact with moist air.

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Question (11)

An iron nail kept only in dry air does not rust because:

Explanation:

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Question (12)

An iron nail dipped completely in boiled water and covered with oil does not rust because:

Explanation:

Link:

Question (13)

Which statement is correct about rusting?

Explanation:

Link:

Question (14)

The gradual deterioration of metal surfaces due to air, water, or other substances is called:

Explanation:

Link:

Question (15)

A green coating is commonly formed on the surface of:

Explanation:

Link:

Question (16)

A black coating develops on objects made of:

Explanation:

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Question (17)

Which of the following is an example of corrosion?

Explanation:

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Question (18)

Rusting is considered a serious problem because it:

Explanation:

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Question (19)

Large amounts of money are spent every year mainly to:

Explanation:

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Question (20)

Which method can prevent rusting of iron?

Explanation:

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