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Question (1)

QN0026406

A student mixes 5 g of sodium carbonate with 10 g of hydrochloric acid in a closed flask. After reaction, the total mass of the flask and contents is found to be:

(A) Less than 15 g
(B) More than 15 g
(C) Equal to 15 g
(D) Zero

Correct Answer: C

Explanation:

In a closed system, mass remains conserved during chemical reactions.

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Question (2)

QN0026407

Which pair of elements will most likely form an ionic compound?

(A) Carbon and oxygen
(B) Hydrogen and chlorine
(C) Sodium and chlorine
(D) Nitrogen and oxygen

Correct Answer: C

Explanation:

Ionic compounds form mainly between metals and non-metals through electron transfer.

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Question (3)

QN0026408

The mass ratio of hydrogen to oxygen in water is always:

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

Correct Answer: C

Explanation:

In H₂O, 2 g hydrogen combines with 16 g oxygen.

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Question (4)

QN0026409

The molecular mass of methane (CH₄) is:

(A) 12 u
(B) 14 u
(C) 16 u
(D) 18 u

Correct Answer: C

Explanation:

12 + (4 × 1) = 16 u

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Question (5)

QN0026410

A compound contains 24 g carbon and 64 g oxygen. The carbon : oxygen ratio is:

(A) 3 : 8
(B) 8 : 3
(C) 1 : 4
(D) 2 : 5

Correct Answer: A

Explanation:

Divide both by 8 → 24:64 = 3:8

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Question (6)

QN0026411

Which statement correctly explains Dalton’s Atomic Theory?

(A) Atoms can be created during reactions
(B) Atoms combine in simple whole-number ratios
(C) Atoms have no mass
(D) Atoms are visible particles

Correct Answer: B

Explanation:

Dalton explained compound formation using whole-number combinations of atoms.

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Question (7)

QN0026412

The valency of nitrogen in ammonia (NH₃) is:

(A) 1
(B) 2
(C) 3
(D) 5

Correct Answer: C

Explanation:

Nitrogen combines with three hydrogen atoms.

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Question (8)

QN0026413

Which compound will conduct electricity in molten state?

(A) Carbon dioxide
(B) Methane
(C) Sodium chloride
(D) Hydrogen

Correct Answer: C

Explanation:

Ionic compounds conduct electricity in molten state due to free ions.

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Question (9)

QN0026414

The formula of aluminium sulfate is:

(A) AlSO₄
(B) Al₂(SO₄)₃
(C) Al₃SO₄
(D) Al(SO₄)₂

Correct Answer: B

Explanation:

Aluminium valency = 3, sulfate valency = 2.

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Question (10)

QN0026415

If 44 g carbon dioxide is formed completely, the mass of oxygen present in it is:

(A) 12 g
(B) 16 g
(C) 22 g
(D) 32 g

Correct Answer: D

Explanation:

CO₂ contains 12 g carbon and 32 g oxygen.

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Question (1)

A student mixes 5 g of sodium carbonate with 10 g of hydrochloric acid in a closed flask. After reaction, the total mass of the flask and contents is found to be:

Explanation:

Link:

Question (2)

Which pair of elements will most likely form an ionic compound?

Explanation:

Link:

Question (3)

The mass ratio of hydrogen to oxygen in water is always:

Explanation:

Link:

Question (4)

The molecular mass of methane (CH₄) is:

Explanation:

Link:

Question (5)

A compound contains 24 g carbon and 64 g oxygen. The carbon : oxygen ratio is:

Explanation:

Link:

Question (6)

Which statement correctly explains Dalton’s Atomic Theory?

Explanation:

Link:

Question (7)

The valency of nitrogen in ammonia (NH₃) is:

Explanation:

Link:

Question (8)

Which compound will conduct electricity in molten state?

Explanation:

Link:

Question (9)

The formula of aluminium sulfate is:

Explanation:

Link:

Question (10)

If 44 g carbon dioxide is formed completely, the mass of oxygen present in it is:

Explanation:

Link:

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