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Question (21)

QN007181

In the sodium sulfate–barium chloride activity, why should both conical flasks remain on the balance during transfer?

(A) To increase reaction speed
(B) To avoid contamination
(C) To prevent mass error due to sticking solution
(D) To cool the reaction

Correct Answer: C

Explanation:

Small traces of solution may remain stuck during transfer.

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Question (22)

QN007182

Which of the following best explains conservation of mass using Dalton’s Atomic Theory?

(A) Atoms disappear during reactions
(B) Atoms are rearranged during reactions
(C) Atoms melt during reactions
(D) New atoms are created during reactions

Correct Answer: B

Explanation:

Atoms are neither created nor destroyed; they rearrange.

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Question (23)

QN007183

If 8 g oxygen combines completely with carbon to form carbon dioxide, the mass of carbon used is:

(A) 2 g
(B) 3 g
(C) 4 g
(D) 6 g

Correct Answer: B

Explanation:

32 g oxygen combines with 12 g carbon, so 8 g combines with 3 g.

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Question (24)

QN007184

During dissolution of salt in water, the total mass after dissolving is equal to:

(A) Mass of water only
(B) Mass of salt only
(C) Sum of masses of salt and water
(D) Difference of masses of salt and water

Correct Answer: C

Explanation:

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Question (25)

QN007185

The Law of Conservation of Mass applies to:

(A) Only physical changes
(B) Only chemical changes
(C) Both physical and chemical changes
(D) Only nuclear reactions

Correct Answer: C

Explanation:

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Question (26)

QN007186

If 2.4 g carbon reacts completely with oxygen, the mass of carbon dioxide formed is:

(A) 4.4 g
(B) 6.6 g
(C) 8.8 g
(D) 10.2 g

Correct Answer: C

Explanation:

(44 × 2.4)/12 = 8.8 g.

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Question (27)

QN007187

Which scientist is known as the Father of Modern Chemistry?

(A) Dalton
(B) Bohr
(C) Rutherford
(D) Lavoisier

Correct Answer: D

Explanation:

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Question (28)

QN007188

A reaction produces 3.5 g carbon dioxide, 1.5 g water and 5 g salt. Total mass of reactants must be:

(A) 8.5 g
(B) 9.0 g
(C) 10.0 g
(D) 11.0 g

Correct Answer: C

Explanation:

Total product mass = 3.5 + 1.5 + 5 = 10 g.

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Question (29)

QN007189

Which observation in Activity 9.2 confirms gas formation?

(A) Colour disappears
(B) Precipitate forms
(C) Balloon inflates
(D) Salt dissolves

Correct Answer: C

Explanation:

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Question (30)

QN007190

The reaction between baking soda and vinegar demonstrates conservation of mass only when:

(A) Reaction is heated strongly
(B) Gas is allowed to escape
(C) System remains closed
(D) Vinegar is diluted

Correct Answer: C

Explanation:

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Question (21)

In the sodium sulfate–barium chloride activity, why should both conical flasks remain on the balance during transfer?

Explanation:

Link:

Question (22)

Which of the following best explains conservation of mass using Dalton’s Atomic Theory?

Explanation:

Link:

Question (23)

If 8 g oxygen combines completely with carbon to form carbon dioxide, the mass of carbon used is:

Explanation:

Link:

Question (24)

During dissolution of salt in water, the total mass after dissolving is equal to:

Explanation:

Link:

Question (25)

The Law of Conservation of Mass applies to:

Explanation:

Link:

Question (26)

If 2.4 g carbon reacts completely with oxygen, the mass of carbon dioxide formed is:

Explanation:

Link:

Question (27)

Which scientist is known as the Father of Modern Chemistry?

Explanation:

Link:

Question (28)

A reaction produces 3.5 g carbon dioxide, 1.5 g water and 5 g salt. Total mass of reactants must be:

Explanation:

Link:

Question (29)

Which observation in Activity 9.2 confirms gas formation?

Explanation:

Link:

Question (30)

The reaction between baking soda and vinegar demonstrates conservation of mass only when:

Explanation:

Link:

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