A mixed oxide of iron and chromium is fused with sodium carbonate in free access of air to from a yellow, coloured compound (A). On acidification the compounf (A) froms an orange coloured compound (B), which is a strong oxidizing agent. Identify compound (A) and (B). Write chemical reactions involved.

Explanation

To solve the problem step by step, we will identify the compounds (A) and (B) formed during the reactions involving a mixed oxide of iron and chromium, sodium carbonate, and acidification.

### Step 1: Identify the Mixed Oxide
The mixed oxide of iron and chromium is known as chromite ore, which has the formula:
\[ \text{FeCr}_2\text{O}_4 \]

### Step 2: Reaction with Sodium Carbonate and Air
When chromite ore is fused with sodium carbonate (Na2CO3) in the presence of excess air (O2), it undergoes oxidation and forms sodium chromate (Na2CrO4), along with iron(III) oxide (Fe2O3) and carbon dioxide (CO2). The reaction can be written as follows:
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