How would you prepare the following?
(i) Sodium thiosulphate from sodium carbonate
(ii) Sodium carbonate from sodium chloride
(iii) Microcosmic salt from disodium hydrogen phosphate

Explanation

To prepare the compounds mentioned in the question, we will follow the steps outlined below for each compound.

### (i) Preparation of Sodium Thiosulphate from Sodium Carbonate

1. **React Sodium Carbonate with Sulfur Dioxide**:
- Start with sodium carbonate (Na2CO3) and pass sulfur dioxide (SO2) over it.
- The reaction is as follows:
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