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Question (21)

QN007231

The fixed ratio in which elements combine in a compound is determined by:

(A) Volume only
(B) Number of molecules only
(C) Mass of constituent elements
(D) Colour of elements

Correct Answer: C

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Question (22)

QN007232

Which of the following is an example of Law of Constant Proportions?

(A) Ice melting into water
(B) Sodium chloride always containing sodium and chlorine in fixed mass ratio
(C) Iron expanding on heating
(D) Water boiling at 100°C

Correct Answer: B

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Question (23)

QN007233

In methane, carbon and hydrogen are present in the ratio 12 : 4 by mass. Simplified ratio is:

(A) 1 : 2
(B) 2 : 1
(C) 3 : 1
(D) 4 : 3

Correct Answer: C

Explanation:

12 : 4 simplifies to 3 : 1.

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Question (24)

QN007234

If 6 g hydrogen combines completely with oxygen to form water, the oxygen required is:

(A) 24 g
(B) 36 g
(C) 42 g
(D) 48 g

Correct Answer: D

Explanation:

1 : 8 ratio gives oxygen = 48 g.

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Question (25)

QN007235

Which of the following compounds contains elements in the ratio 3 : 8 by mass?

(A) Water
(B) Carbon dioxide
(C) Methane
(D) Ammonia

Correct Answer: B

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Question (26)

QN007236

A 90 g sample of water contains 10 g hydrogen. The mass of oxygen present is:

(A) 70 g
(B) 72 g
(C) 80 g
(D) 88 g

Correct Answer: C

Explanation:

90 – 10 = 80 g.

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Question (27)

QN007237

According to the Law of Constant Proportions, a pure chemical compound:

(A) May have variable composition
(B) Always contains same elements in same mass ratio
(C) Exists only in liquid form
(D) Contains equal masses of all elements

Correct Answer: B

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Question (28)

QN007238

If carbon monoxide contains carbon and oxygen in the ratio 3 : 4 by mass, then 24 g oxygen combines with carbon mass:

(A) 6 g
(B) 12 g
(C) 18 g
(D) 20 g

Correct Answer: C

Explanation:

3 : 4 = x : 24, so x = 18 g.

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Question (29)

QN007239

Which observation best supports Proust’s law?

(A) Water boils at 100°C
(B) Pure compounds have fixed composition
(C) Metals conduct electricity
(D) Acids turn blue litmus red

Correct Answer: B

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Question (30)

QN007240

In a sample of carbon dioxide, oxygen constitutes:

(A) 27.3%
(B) 50%
(C) 72.7%
(D) 80%

Correct Answer: C

Explanation:

(32/44) × 100 = 72.7%.

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Question (21)

The fixed ratio in which elements combine in a compound is determined by:

Explanation:

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Question (22)

Which of the following is an example of Law of Constant Proportions?

Explanation:

Link:

Question (23)

In methane, carbon and hydrogen are present in the ratio 12 : 4 by mass. Simplified ratio is:

Explanation:

Link:

Question (24)

If 6 g hydrogen combines completely with oxygen to form water, the oxygen required is:

Explanation:

Link:

Question (25)

Which of the following compounds contains elements in the ratio 3 : 8 by mass?

Explanation:

Link:

Question (26)

A 90 g sample of water contains 10 g hydrogen. The mass of oxygen present is:

Explanation:

Link:

Question (27)

According to the Law of Constant Proportions, a pure chemical compound:

Explanation:

Link:

Question (28)

If carbon monoxide contains carbon and oxygen in the ratio 3 : 4 by mass, then 24 g oxygen combines with carbon mass:

Explanation:

Link:

Question (29)

Which observation best supports Proust’s law?

Explanation:

Link:

Question (30)

In a sample of carbon dioxide, oxygen constitutes:

Explanation:

Link:

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