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Question (11)

QN0026416

Which property is generally shown by covalent compounds?

(A) High electrical conductivity
(B) High melting point
(C) Low boiling point
(D) Solubility in water

Correct Answer: C

Explanation:

Covalent compounds usually have weak intermolecular forces.

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Question (12)

QN0026417

The formula unit mass of magnesium chloride (MgCl₂) is:

(A) 71 u
(B) 95 u
(C) 111 u
(D) 143 u

Correct Answer: B

Explanation:

24 + (2 × 35.5) = 95 u

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Question (13)

QN0026418

Which statement about atoms is scientifically correct today?

(A) Atoms are indivisible under all conditions
(B) Atoms can be split into subatomic particles
(C) Atoms have no internal structure
(D) All atoms have same mass

Correct Answer: B

Explanation:

Discovery of electrons, protons and neutrons disproved indivisibility.

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Question (14)

QN0026419

The chemical formula of ammonium nitrate is:

(A) NH₄NO₂
(B) NH₄NO₃
(C) (NH₄)₂NO₃
(D) NH₃NO₃

Correct Answer: B

Explanation:

Ammonium ion is NH₄⁺ and nitrate ion is NO₃⁻.

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Question (15)

QN0026420

A student heats 100 g limestone and obtains 56 g calcium oxide and carbon dioxide gas. The mass of carbon dioxide released is:

(A) 24 g
(B) 36 g
(C) 44 g
(D) 56 g

Correct Answer: C

Explanation:

100 − 56 = 44 g

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Question (16)

QN0026421

Which of the following compounds contains only covalent bonds?

(A) NaCl
(B) MgO
(C) CO₂
(D) CaCl₂

Correct Answer: C

Explanation:

Carbon and oxygen are non-metals and share electrons.

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Question (17)

QN0026422

The molecular mass of sulfuric acid (H₂SO₄) is:

(A) 82 u
(B) 96 u
(C) 98 u
(D) 100 u

Correct Answer: C

Explanation:

(2 × 1) + 32 + (4 × 16) = 98 u

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Question (18)

QN0026423

Which observation best indicates a chemical reaction?

(A) Change in shape
(B) Evolution of gas
(C) Dissolving of sugar
(D) Melting of wax

Correct Answer: B

Explanation:

Gas evolution is a common sign of chemical change.

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Question (19)

QN0026424

The total number of atoms present in one molecule of phosphoric acid (H₃PO₄) is:

(A) 5
(B) 6
(C) 7
(D) 8

Correct Answer: D

Explanation:

3 H + 1 P + 4 O = 8 atoms

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Question (20)

QN0026425

Which statement correctly compares ionic and covalent compounds?

(A) Both conduct electricity in solid state
(B) Ionic compounds contain ions; covalent compounds contain molecules
(C) Covalent compounds always dissolve in water
(D) Ionic compounds have low melting points

Correct Answer: B

Explanation:

Ionic compounds are made of oppositely charged ions, while covalent compounds consist of molecules formed by sharing electrons.

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Question (11)

Which property is generally shown by covalent compounds?

Explanation:

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Question (12)

The formula unit mass of magnesium chloride (MgCl₂) is:

Explanation:

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Question (13)

Which statement about atoms is scientifically correct today?

Explanation:

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Question (14)

The chemical formula of ammonium nitrate is:

Explanation:

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Question (15)

A student heats 100 g limestone and obtains 56 g calcium oxide and carbon dioxide gas. The mass of carbon dioxide released is:

Explanation:

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Question (16)

Which of the following compounds contains only covalent bonds?

Explanation:

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Question (17)

The molecular mass of sulfuric acid (H₂SO₄) is:

Explanation:

Link:

Question (18)

Which observation best indicates a chemical reaction?

Explanation:

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Question (19)

The total number of atoms present in one molecule of phosphoric acid (H₃PO₄) is:

Explanation:

Link:

Question (20)

Which statement correctly compares ionic and covalent compounds?

Explanation:

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