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 (II) chloride and Iron (III) chloride

B) Ferrous chloride and ferric chloride only

C) Iron chloride and iron trichloride

D) Iron dichloride and iron trichloride

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) Cuprous oxide and cupric oxide only in common system

B) Copper monoxide and copper dioxide

C) Copper oxide and copper peroxide

D) Copper (I) oxide and Copper (II) oxide

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 all metals always need Roman numerals.

B) Because chlorine has variable oxidation states.

C) Because chlorine determines the compound name.

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

4 / 20

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

A) Oxygen has oxidation state - 4.

B) The compound contains four oxygen atoms only.

C) Lead has four atoms in the compound.

D) Lead has oxidation state + 4.

5 / 20

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

A) Manganese dioxide only

B) Manganese oxide

C) Manganese (II) oxide

D) Manganese (IV) 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 + 3.

B) Metal has oxidation state + 2.

C) Chlorine has oxidation state + 3.

D) Metal has oxidation state + 1.

7 / 20

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

A) To indicate oxidation state of metals with variable valency

B) To indicate molecular mass

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) Cu₂Cl₃

B) Cu₂Cl

C) CuCl

D) CuCl₂

9 / 20

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

A) They have different physical states

B) Chlorine changes its valency

C) Iron shows different oxidation states in each compound

D) They contain different types of bonding only

10 / 20

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

A) Tin tetrachloride only

B) Tin (IV) chloride

C) Tin (II) chloride

D) Tin chloride

11 / 20

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

A) 0

B) + 1

C) - 1

D) + 2

12 / 20

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

A) They always form ionic bonds only.

B) They show variable oxidation states.

C) They have fixed atomic mass.

D) They are non-metals.

13 / 20

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

A) It shows wrong formula.

B) It does not specify oxidation state of iron.

C) It is a non-IUPAC name.

D) It ignores chlorine presence.

14 / 20

Which compound name correctly uses Roman numerals?

A) Calcium (II) oxide

B) Sodium (II) chloride

C) Potassium (IV) chloride

D) Iron (III) oxide

15 / 20

In CuO, what does Copper (II) indicate?

A) Copper has + 1 charge.

B) Oxygen has variable valency.

C) Oxygen has + 2 charge.

D) Copper 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 Latin names are banned.

C) Because oxygen determines naming.

D) To standardize oxidation state representation internationally.

17 / 20

Which statement about Fe₂O₃ is correct?

A) Iron is in + 2 oxidation state.

B) Iron has zero oxidation state.

C) Oxygen is positive.

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 element shows only one fixed oxidation state.

B) When compound contains oxygen.

C) When compound is ionic.

D) When element shows multiple oxidation states.

20 / 20

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

A) Because iron is in + 3 oxidation state.

B) Because compound is covalent.

C) Because iron is in elemental form.

D) Because chlorine is trivalent.

Your score is

0%