What is the valency of the metal in the following formulae?
(a) `CaCl_(2)`, (b) `Na_(2)O`, ( c) `Fe_(2)O_(3)`

Explanation

To determine the valency of the metals in the given compounds, we will analyze each formula step by step.

### Step-by-Step Solution:

**(a) For `CaCl₂`:**
1. Identify the metal and non-metal in the compound. Here, Calcium (Ca) is the metal and Chlorine (Cl) is the non-metal.
2. The formula indicates that there are 2 Chlorine atoms for every 1 Calcium atom.
3. To find the valency of Calcium, we can use the crisscross method. The number of Chlorine atoms (2) becomes the valency of Calcium.
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