Chemistry 9th Chap 7 : Topic 6 - Maryam Publications

Chemistry Chapter 7 : Topic 6

Monatomic Ion Charges

1 / 20

Which statement best explains why the oxidation number of a monatomic ion is equal to its charge?

A) Because the ion has gained or lost electrons, resulting in a net charge.

B) Because oxidation number is randomly assigned in compounds.

C) Because all ions have oxidation number zero in free state.

D) Because oxidation number depends only on atomic mass.

2 / 20

What is the oxidation number of Na⁺ ion?

A) - 1

B) + 2

C) + 1

D) 0

3 / 20

A chloride ion (Cl⁻) has which oxidation number?

A) - 1

B) + 1

C) 0

D) + 2

4 / 20

Which conclusion is correct about monatomic ions?

A) Their oxidation number differs from their charge.

B) Their oxidation number equals their ionic charge.

C) Their oxidation number depends on bonding type.

D) Their oxidation number is always zero.

5 / 20

A magnesium ion has a charge of + 2. Its oxidation number is:

A) - 2

B) 0

C) + 2

D) + 1

6 / 20

Which statement is FALSE regarding monatomic ions?

A) Their oxidation number equals their charge

B) They carry a net charge

C) They always have oxidation number zero

D) They are formed by electron transfer

7 / 20

The oxidation number of Al³⁺ is:

A) + 3

B) + 1

C) 0

D) - 3

8 / 20

Why is the oxidation number of a monatomic ion always equal to its charge?

A) Because protons determine oxidation number

B) Because ions are always neutral

C) Because ions have fixed atomic mass

D) Because oxidation number counts electrons lost or gained

9 / 20

Which species has oxidation number - 2?

A) O²⁻

B) Na⁺

C) Ca²⁺

D) Al³⁺

10 / 20

A student says “oxidation number of an ion is unrelated to its charge.” This statement is:

A) Depends on compound

B) Incorrect

C) Partially correct

D) Correct

11 / 20

Which is the correct oxidation number for Fe²⁺?

A) - 2

B) + 2

C) 0

D) + 3

12 / 20

In the ion Cl⁻, the oxidation number represents:

A) Gain of one proton

B) Gain of one electron

C) Loss of one electron

D) Loss of one neutron

13 / 20

Which statement correctly compares charge and oxidation number for monatomic ions?

A) They are numerically equal

B) Charge is always double oxidation number

C) They are unrelated

D) Charge is always zero

14 / 20

Consider the statement: “A monatomic ion with charge + 3 will always have oxidation number + 3.” This is:

A) Depends on element type

B) Sometimes true

C) False

D) True

15 / 20

Which ion has the greatest positive oxidation number?

A) Mg²⁺

B) Al³⁺

C) Na⁺

D) Cl⁻

16 / 20

A monatomic ion is best defined as:

A) A compound of metals and non-metals

B) A single atom with a charge

C) A neutral atom in gaseous state

D) A molecule with multiple atoms

17 / 20

Why is oxidation number important for monatomic ions?

A) It predicts melting point

B) It shows number of bonds formed

C) It determines atomic radius

D) It indicates electron gain or loss

18 / 20

Which pair has equal magnitude but opposite oxidation numbers?

A) Cl⁻ and O²⁻

B) Na⁺ and Mg²⁺

C) Na⁺ and Cl⁻

D) Al³⁺ and Fe²⁺

19 / 20

In monatomic ions, oxidation number is determined by:

A) Number of neutrons

B) Mass number

C) Atomic number

D) Net ionic charge

20 / 20

Which explanation best supports the idea that oxidation number equals charge?

A) Ions become neutral in compounds

B) Atoms change their protons during ion formation

C) Electrons are transferred, creating measurable charge

D) Oxidation number is always positive

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