A mixed oxide of iron and chromium, `FeO.Cr_2O_3` is fused with sodium carbonate in the presence of air to form a yellow compound (A). On acidification, the compound (A) forms an orange coloured compound (B) which is a strong oxidising agent. Identify
(i) the compounds (A) and (B)
(ii) write balanced chemical equations for each step.

Explanation

To solve the problem step by step, we will identify the compounds (A) and (B) and write the balanced chemical equations for each step.

### Step 1: Identify Compound (A)
Given the mixed oxide of iron and chromium, `FeO.Cr2O3`, when fused with sodium carbonate (Na2CO3) in the presence of air, it forms a yellow compound (A).

The reaction can be represented as:
\[ \text{FeO} \cdot \text{Cr}_2\text{O}_3 + \text{Na}_2\text{CO}_3 + \text{O}_2 \rightarrow \text{Na}_2\text{CrO}_4 + \text{Fe}_2\text{O}_3 + \text{CO}_2 \]

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