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(a) When a chromite ore (A) is fused wit...

(a) When a chromite ore (A) is fused with an aqueous solution of sodium carbonate in free excess of air, a yellow solution of compound (B) is obtained. This solution is filtered and acidified with sulphuric acid to form compound (C). Compound (C) on treatment with solution of KCl gives orange crystals of compound (D). Write the chemical formulae of compounds A to D.
(b) Describe the cause of the following variations with respect to lanthanoids and actinoids:
(i) Greater range of oxidation states of actinoids as compared to lanthanoids.
(ii) Greater actinoid contraction as compared to lanthanoid contraction.
(iii) Lower ionisation enthalpy of early actinoids as compared to the early lanthanoids.

Text Solution

AI Generated Solution

### Step-by-Step Solution: **Part (a)** 1. **Identify Compound A**: The chromite ore is represented as FeCrO4 (chromite). - **Chemical Formula**: A = FeCrO4 2. **Reaction of Compound A with Sodium Carbonate**: When chromite ore (FeCrO4) is fused with sodium carbonate (Na2CO3) in the presence of excess air (O2), it forms sodium chromate (Na2CrO4), iron(III) oxide (Fe2O3), and carbon dioxide (CO2). ...
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