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Question (31)

QN007241

If a compound has 7 g nitrogen and 8 g oxygen, the nitrogen : oxygen ratio is:

(A) 7 : 8
(B) 8 : 7
(C) 1 : 8
(D) 3 : 8

Correct Answer: A

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Question (32)

QN007242

Which pair of laws together explain chemical reactions at Class 9 level?

(A) Conservation of Mass and Constant Proportions
(B) Newton’s Laws
(C) Boyle’s and Charles’ Laws
(D) Kepler’s Laws

Correct Answer: A

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Question (33)

QN007243

In water, oxygen percentage by mass is approximately:

(A) 11.1%
(B) 50%
(C) 80%
(D) 88.9%

Correct Answer: D

Explanation:

(16/18) × 100 = 88.9%

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Question (34)

QN007244

Which statement is false regarding the Law of Constant Proportions?

(A) Composition of a compound is fixed
(B) Ratio by mass remains same
(C) Composition changes with source
(D) Pure compounds obey the law

Correct Answer: C

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Question (35)

QN007245

If 18 g water contains 16 g oxygen, hydrogen present is:

(A) 1 g
(B) 2 g
(C) 4 g
(D) 8 g

Correct Answer: B

Explanation:

18 – 16 = 2 g.

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Question (36)

QN007246

The Law of Constant Proportions applies only to:

(A) Mixtures
(B) Pure compounds
(C) Elements only
(D) Solutions only

Correct Answer: B

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Question (37)

QN007247

A compound contains 21 g nitrogen and 24 g oxygen. Simplest mass ratio is:

(A) 7 : 8
(B) 8 : 7
(C) 3 : 4
(D) 4 : 3

Correct Answer: A

Explanation:

21 : 24 simplifies to 7 : 8.

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Question (38)

QN007248

If carbon dioxide from two different laboratories shows the same carbon : oxygen mass ratio, it supports:

(A) Conservation of Energy
(B) Constant Proportions
(C) Radioactivity
(D) Electrolysis

Correct Answer: B

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Question (39)

QN007249

The ratio of hydrogen to oxygen in 36 g water is:

(A) 1 : 2
(B) 1 : 4
(C) 1 : 8
(D) 8 : 1

Correct Answer: C

Explanation:

Water always has H : O = 1 : 8 by mass.

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Question (40)

QN007250

Which among the following is a conceptual application of the Law of Constant Proportions?

(A) Identifying purity of a compound
(B) Measuring room temperature
(C) Determining boiling point of alcohol
(D) Finding density of wood

Correct Answer: A

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Question (31)

If a compound has 7 g nitrogen and 8 g oxygen, the nitrogen : oxygen ratio is:

Explanation:

Link:

Question (32)

Which pair of laws together explain chemical reactions at Class 9 level?

Explanation:

Link:

Question (33)

In water, oxygen percentage by mass is approximately:

Explanation:

Link:

Question (34)

Which statement is false regarding the Law of Constant Proportions?

Explanation:

Link:

Question (35)

If 18 g water contains 16 g oxygen, hydrogen present is:

Explanation:

Link:

Question (36)

The Law of Constant Proportions applies only to:

Explanation:

Link:

Question (37)

A compound contains 21 g nitrogen and 24 g oxygen. Simplest mass ratio is:

Explanation:

Link:

Question (38)

If carbon dioxide from two different laboratories shows the same carbon : oxygen mass ratio, it supports:

Explanation:

Link:

Question (39)

The ratio of hydrogen to oxygen in 36 g water is:

Explanation:

Link:

Question (40)

Which among the following is a conceptual application of the Law of Constant Proportions?

Explanation:

Link:

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