Oxidation number of an element can be zero but valency is never zero.

Explanation

To determine whether the statement "Oxidation number of an element can be zero but valency is never zero" is true or false, we will analyze the concepts of oxidation number and valency step by step.

### Step 1: Understanding Oxidation Number
- The oxidation number (or oxidation state) of an element in a compound indicates the degree of oxidation (loss of electrons) of that element.
- The oxidation number can indeed be zero. For example, in elemental forms like O2 (oxygen gas) or N2 (nitrogen gas), the oxidation number of each atom is zero because they are not combined with other elements and have not lost or gained any electrons.

**Hint:** Look for examples of elements in their elemental form to understand oxidation numbers.

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