(a) Complete the following chemical equations:
(i) ` Cr_(2) O_(7)^(2-) (aq) + H_(2) S(g) + H^(+) (aq) to `
(ii) ` Cu^(2+)(aq) + I^(-) (aq) to `
(b) How would you account for the following :
(i) The oxidising power of oxoanions are in the order `VO_(2)^(+) lt Cr_(2)O_(7)^(2-) lt Mn O_(4)^(-) `
(ii) The third ionization enthalpy of manganess (Z = 25) is exceptionally high.
(iii) `Cr^(2+)` is a stronger reducing agent than `Fe^(2+)`.

Explanation

### Step-by-Step Solution

#### Part (a): Complete the following chemical equations

**(i)** The first equation is:
\[ \text{Cr}_2\text{O}_7^{2-} (aq) + \text{H}_2\text{S} (g) + \text{H}^+ (aq) \rightarrow \]

To balance this redox reaction, we need to identify the oxidation and reduction half-reactions.
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