0.5 g sample of copper ore is converted into `CuSO_4` solution. The resulting solution is acidified with dilute `CH_3COOH` (acetic acid) and excess KI added. The liberated `I_2` required 0.248 g `Na_2S_2O_3.5H_2O` for complete reaction. Calculate the percantage of Cu in the ore.

Explanation

To calculate the percentage of copper (Cu) in the ore sample, we can follow these steps:

### Step 1: Calculate the equivalents of \( \text{Na}_2\text{S}_2\text{O}_3 \cdot 5\text{H}_2\text{O} \)

Given that 0.248 g of \( \text{Na}_2\text{S}_2\text{O}_3 \cdot 5\text{H}_2\text{O} \) is used, we first need to find its molar mass.

- Molar mass of \( \text{Na}_2\text{S}_2\text{O}_3 \cdot 5\text{H}_2\text{O} \):
- Na: 22.99 g/mol (2 Na = 45.98 g/mol)
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