What do you understand by variable valency'? Give two examples of metals and two examples of non-metals showing variable valency.

Explanation

### Step-by-Step Text Solution:

**Step 1: Understanding Valency**
- Valency refers to the combining capacity of an element with other elements. It indicates how many electrons an atom can lose, gain, or share when forming chemical bonds.

**Step 2: Defining Variable Valency**
- Variable valency is when an element can exhibit more than one valency in different compounds. This means that the element can exist in different oxidation states depending on the compound it forms.

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