Chemistry 9th Chap 7 : Topic 2 - Maryam Publications

Chemistry Chapter 7 : Topic 2

Oxidation Number Naming

1 / 20

In modern chemical nomenclature, transition metals often show variable oxidation states. For example, iron can form Fe²⁺ and Fe³⁺ ions. Which naming system correctly distinguishes between these two compounds FeCl₂ and FeCl₃?

A) Iron dichloride and iron trichloride

B) Iron (II) chloride and Iron (III) chloride

C) Iron chloride and iron trichloride

D) Ferrous chloride and ferric chloride only

2 / 20

A student is given two compounds Cu₂O and CuO. Both contain copper but show different chemical behavior. Which naming correctly uses Roman numerals to represent their oxidation states?

A) Copper monoxide and copper dioxide

B) Copper (I) oxide and Copper (II) oxide

C) Cuprous oxide and cupric oxide only in common system

D) Copper oxide and copper peroxide

3 / 20

Why is it necessary to use Roman numerals in naming compounds like FeCl₂ and FeCl₃ instead of a single fixed name like “iron chloride”?

A) Because chlorine has variable oxidation states.

B) Because iron shows multiple oxidation states and forms different compounds.

C) Because chlorine determines the compound name.

D) Because all metals always need Roman numerals.

4 / 20

A compound is named as “Lead (IV) oxide”. What does the Roman numeral (IV) indicate?

A) Lead has four atoms in the compound.

B) Oxygen has oxidation state - 4.

C) The compound contains four oxygen atoms only.

D) Lead has oxidation state + 4.

5 / 20

Which of the following correctly represents the name of MnO₂ using Stock nomenclature?

A) Manganese (IV) oxide

B) Manganese (II) oxide

C) Manganese dioxide only

D) Manganese oxide

6 / 20

A compound contains a metal that can show + 1 and + 3 oxidation states. If the compound is named as Metal (III) chloride, what does this mean?

A) Metal has oxidation state + 2.

B) Chlorine has oxidation state + 3.

C) Metal has oxidation state + 1.

D) Metal has oxidation state + 3.

7 / 20

Which statement best explains the purpose of using Roman numerals in chemical names?

A) To indicate molecular mass

B) To indicate oxidation state of metals with variable valency

C) To show number of atoms in a molecule

D) To show physical state of the compound

8 / 20

A compound is named Copper (I) chloride. Which formula correctly represents it?

A) CuCl₂

B) Cu₂Cl₃

C) Cu₂Cl

D) CuCl

9 / 20

Iron forms two chlorides FeCl₂ and FeCl₃. Why do they require different names in Stock system?

A) Chlorine changes its valency

B) They contain different types of bonding only

C) They have different physical states

D) Iron shows different oxidation states in each compound

10 / 20

Which of the following is the correct IUPAC name of SnCl₄?

A) Tin chloride

B) Tin (II) chloride

C) Tin tetrachloride only

D) Tin (IV) chloride

11 / 20

A compound is named “Mercury (I) chloride”. This indicates that mercury is present in which oxidation state?

A) - 1

B) 0

C) + 2

D) + 1

12 / 20

Which feature of transition metals makes Roman numerals necessary in their naming?

A) They always form ionic bonds only.

B) They are non-metals.

C) They show variable oxidation states.

D) They have fixed atomic mass.

13 / 20

A student writes “Iron chloride” for FeCl₃. Why is this name considered incomplete?

A) It ignores chlorine presence.

B) It is a non-IUPAC name.

C) It does not specify oxidation state of iron.

D) It shows wrong formula.

14 / 20

Which compound name correctly uses Roman numerals?

A) Calcium (II) oxide

B) Sodium (II) chloride

C) Iron (III) oxide

D) Potassium (IV) chloride

15 / 20

In CuO, what does Copper (II) indicate?

A) Copper has + 1 charge.

B) Oxygen has variable valency.

C) Copper has + 2 charge.

D) Oxygen has + 2 charge.

16 / 20

Why is Copper (I) oxide written instead of simply “cuprous oxide” in modern nomenclature?

A) Because cuprous is incorrect chemically.

B) Because oxygen determines naming.

C) To standardize oxidation state representation internationally.

D) Because Latin names are banned.

17 / 20

Which statement about Fe₂O₃ is correct?

A) Iron is in + 2 oxidation state.

B) Oxygen is positive.

C) Iron has zero oxidation state.

D) Iron is in + 3 oxidation state.

18 / 20

A compound is named “Lead (II) nitrate”. What does this tell about lead?

A) Lead has - 2 oxidation state.

B) Lead has + 2 oxidation state.

C) Lead is neutral.

D) Lead has + 4 oxidation state.

19 / 20

Which situation makes Roman numerals unnecessary in chemical naming?

A) When compound contains oxygen.

B) When element shows multiple oxidation states.

C) When compound is ionic.

D) When element shows only one fixed oxidation state.

20 / 20

Why is FeCl₃ called Iron (III) chloride instead of Iron chloride?

A) Because chlorine is trivalent.

B) Because iron is in elemental form.

C) Because compound is covalent.

D) Because iron is in + 3 oxidation state.

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