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Question (31)

QN007191

If 15 g of a compound decomposes into 9 g and 6 g products, the reaction obeys conservation of mass because:

(A) Products are lighter
(B) Total product mass equals reactant mass
(C) Gases were produced
(D) Matter vanished

Correct Answer: B

Explanation:

9 g + 6 g = 15 g.

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Question (32)

QN007192

Which among the following is NOT a reason for apparent decrease in mass during a reaction?

(A) Escape of gas
(B) Experimental error
(C) Closed container
(D) Evaporation of volatile substances

Correct Answer: C

Explanation:

A closed container prevents loss of matter.

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Question (33)

QN007193

The statement “Matter can neither be created nor destroyed in a chemical reaction” is the exact wording of:

(A) Law of Constant Proportions
(B) Dalton’s Atomic Theory
(C) Law of Conservation of Mass
(D) Avogadro’s Law

Correct Answer: C

Explanation:

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Question (34)

QN007194

If reactants weigh 75 g and one gaseous product escapes, the measured product mass in an open container may:

(A) Become more than 75 g
(B) Become equal to 75 g
(C) Become less than 75 g
(D) Become zero

Correct Answer: C

Explanation:

Escaping gas reduces measured product mass.

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Question (35)

QN007195

Which apparatus is specifically mentioned in the activities for accurate mass measurement?

(A) Spring balance
(B) Physical balance
(C) Digital weighing balance
(D) Beam balance

Correct Answer: C

Explanation:

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Question (36)

QN007196

A student obtains 12.5 g products from 13 g reactants in an open setup. The missing mass is most likely due to:

(A) Destruction of atoms
(B) Escape of gaseous products
(C) Fault in chemical equation
(D) Conversion into energy only

Correct Answer: B

Explanation:

Gas escaped from the open setup.

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Question (37)

QN007197

If 14 g nitrogen reacts completely with 6 g hydrogen, the mass of ammonia formed will be:

(A) 14 g
(B) 18 g
(C) 20 g
(D) 24 g

Correct Answer: C

Explanation:

14 + 6 = 20 g.

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Question (38)

QN007198

In the “Think as a Scientist” section, zinc reacts with dilute hydrochloric acid to produce:

(A) Zinc oxide and water
(B) Zinc chloride and hydrogen gas
(C) Zinc sulfate and oxygen
(D) Zinc carbonate and carbon dioxide

Correct Answer: B

Explanation:

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Question (39)

QN007199

Which condition is essential to experimentally verify the Law of Conservation of Mass in gas-evolving reactions?

(A) Use coloured solutions
(B) Use excess reactants
(C) Prevent escape of gas
(D) Keep reaction very slow

Correct Answer: C

Explanation:

The reaction must occur in a closed system.

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Question (40)

QN007200

The sum of masses before and after a chemical reaction remains the same because:

(A) Molecules vanish
(B) Atoms are conserved
(C) Gases are weightless
(D) Solids gain mass automatically

Correct Answer: B

Explanation:

Atoms are only rearranged during reactions.

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Question (31)

If 15 g of a compound decomposes into 9 g and 6 g products, the reaction obeys conservation of mass because:

Explanation:

Link:

Question (32)

Which among the following is NOT a reason for apparent decrease in mass during a reaction?

Explanation:

Link:

Question (33)

The statement “Matter can neither be created nor destroyed in a chemical reaction” is the exact wording of:

Explanation:

Link:

Question (34)

If reactants weigh 75 g and one gaseous product escapes, the measured product mass in an open container may:

Explanation:

Link:

Question (35)

Which apparatus is specifically mentioned in the activities for accurate mass measurement?

Explanation:

Link:

Question (36)

A student obtains 12.5 g products from 13 g reactants in an open setup. The missing mass is most likely due to:

Explanation:

Link:

Question (37)

If 14 g nitrogen reacts completely with 6 g hydrogen, the mass of ammonia formed will be:

Explanation:

Link:

Question (38)

In the “Think as a Scientist” section, zinc reacts with dilute hydrochloric acid to produce:

Explanation:

Link:

Question (39)

Which condition is essential to experimentally verify the Law of Conservation of Mass in gas-evolving reactions?

Explanation:

Link:

Question (40)

The sum of masses before and after a chemical reaction remains the same because:

Explanation:

Link:

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