# What is the oxidation state of chlorine in Cl2O7? (a) -2, (b) +7, (c) -1, (d) +1

By BYJU'S Exam Prep

Updated on: September 25th, 2023

The oxidation state of chlorine in Cl2O7 is +7. The number of charges (positive or negative) assigned to an atom in a molecule or ion in accordance with a set of arbitrary principles determines the oxidation number/oxidation state of that element in a compound.

### Rules for Assigning Oxidation Number

• The monatomic ion’s oxidation number and charge are the same. For instance:
• Oxidation states of Li+, Ca2+ and Al3+ are +1, +2 and +3 respectively.
• The oxidation state of Cl- and SO42- are -1 and -2 respectively.
• With the exception of ionic hydrides, hydrogen has a +1 oxidation state in all compounds (-1 oxidation state).
• The oxygen oxidation state in a compound is -2, with the exception of peroxides, which are -1.
• Alkaline earth metals (Be, Mg, etc.) have +2 oxidation states, but alkali metals (Li, Na, K, etc.) always have +1 oxidation states.

Calculations:

To find:-

Oxidation number of chlorine in Cl2O7

Let the oxidation number of Chlorine (Cl) in Cl2O7 be x.

Based on the above rules,

2x + 7× (-2) = 0

or, 2x -14 = 0

or, x = +7.

Hence, the oxidation state of chlorine in Cl2O7 is +7.

Summary:

## What is the oxidation state of chlorine in Cl2O7? (a) -2, (b) +7, (c) -1, (d) +1

+7 is the oxidation state of chlorine in Cl2O7. All elements in their free form have an oxidation number of zero. Fluorine, the most electronegative element, has an oxidation number of -1 in every molecule.

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