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Question (41)

QN007201

In Activity 9.3, the reaction was performed in an open system because:

(A) Heat was required
(B) No gas was formed
(C) Oxygen had to enter
(D) Solutions were coloured

Correct Answer: B

Explanation:

No gaseous product was formed.

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Question (42)

QN007202

If the mass of products appears greater than the mass of reactants in an open reaction vessel, the most likely explanation is:

(A) Matter was created
(B) Atmospheric gas participated in reaction
(C) Conservation law failed
(D) Balance stopped working completely

Correct Answer: B

Explanation:

Gas from the atmosphere may have combined during reaction.

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Question (43)

QN007203

Which of the following directly supports the Law of Conservation of Mass?

(A) Colour change during reaction
(B) Formation of precipitate
(C) Equal total mass before and after reaction
(D) Increase in temperature

Correct Answer: C

Explanation:

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Question (44)

QN007204

A closed flask contains 25 g reactants. After reaction, 4 g gas and 21 g liquid are present. Which statement is correct?

(A) Law is violated
(B) Total mass after reaction is 21 g
(C) Total mass after reaction is 25 g
(D) Gas has no mass

Correct Answer: C

Explanation:

4 g + 21 g = 25 g.

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Question (45)

QN007205

In the vinegar and baking soda experiment, carbon dioxide is evidence that:

(A) Only physical change occurred
(B) A chemical reaction occurred
(C) Water evaporated
(D) Salt crystallised

Correct Answer: B

Explanation:

Formation of gas indicates a chemical change.

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Question (46)

QN007206

If 9 g water decomposes completely, the masses of hydrogen and oxygen obtained respectively are:

(A) 2 g and 7 g
(B) 1 g and 8 g
(C) 3 g and 6 g
(D) 4 g and 5 g

Correct Answer: B

Explanation:

Water contains hydrogen and oxygen in the ratio 1:8.

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Question (47)

QN007207

Which micro-component of the chapter highlights India’s contribution to nuclear science?

(A) Pause and Ponder
(B) Threads of Curiosity
(C) Bridging Science and Society
(D) At a Glance

Correct Answer: C

Explanation:

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Question (48)

QN007208

Raja Ramanna is associated with:

(A) Discovery of electron
(B) Indian Nuclear Energy Programme
(C) Law of Conservation of Mass
(D) Atomic model of hydrogen

Correct Answer: B

Explanation:

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Question (49)

QN007209

The best evidence that mass is conserved in a reaction is obtained when:

(A) Reactants are coloured
(B) Products are gases only
(C) Reaction occurs in a closed system
(D) Temperature decreases

Correct Answer: C

Explanation:

Closed systems prevent loss of matter.

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Question (50)

QN007210

Which statement is conceptually correct regarding conservation of mass?

(A) Only solids have measurable mass
(B) Gases do not contribute to mass
(C) Total mass remains constant even if state changes occur
(D) Mass changes whenever bubbles form

Correct Answer: C

Explanation:

Mass remains conserved in all physical and chemical changes.

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Question (41)

In Activity 9.3, the reaction was performed in an open system because:

Explanation:

Link:

Question (42)

If the mass of products appears greater than the mass of reactants in an open reaction vessel, the most likely explanation is:

Explanation:

Link:

Question (43)

Which of the following directly supports the Law of Conservation of Mass?

Explanation:

Link:

Question (44)

A closed flask contains 25 g reactants. After reaction, 4 g gas and 21 g liquid are present. Which statement is correct?

Explanation:

Link:

Question (45)

In the vinegar and baking soda experiment, carbon dioxide is evidence that:

Explanation:

Link:

Question (46)

If 9 g water decomposes completely, the masses of hydrogen and oxygen obtained respectively are:

Explanation:

Link:

Question (47)

Which micro-component of the chapter highlights India’s contribution to nuclear science?

Explanation:

Link:

Question (48)

Raja Ramanna is associated with:

Explanation:

Link:

Question (49)

The best evidence that mass is conserved in a reaction is obtained when:

Explanation:

Link:

Question (50)

Which statement is conceptually correct regarding conservation of mass?

Explanation:

Link:

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