What is the valency of Cu in CuO and `Cu_2O`?

Explanation

To determine the valency of copper (Cu) in the compounds CuO and Cu2O, we can follow these steps:

### Step 1: Understand the concept of valency
Valency is the combining capacity of an element, which indicates how many electrons an atom can lose, gain, or share when it forms a chemical bond with other atoms.

### Step 2: Analyze the compound CuO
1. **Identify the elements in CuO**: The compound CuO consists of copper (Cu) and oxygen (O).
2. **Know the charge of oxygen**: Oxygen typically has a valency of -2 (it gains two electrons).
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