Complete and balance the following reactions:
(i). `Zn+NO_3^(ɵ)toZn^(2+)+NH_4^(o+)`
(ii). `Cr_2O_7^(2-)+C_2H_4OtoC_2H_4O_2+Cr^(3+)`

Explanation

To complete and balance the given reactions, we will follow a systematic approach for each reaction.

### Reaction (i):
**Given Reaction:**
\[ \text{Zn} + \text{NO}_3^{-} \rightarrow \text{Zn}^{2+} + \text{NH}_4^{+} \]

#### Step 1: Identify the Reactants and Products
- Reactants: Zinc (Zn) and Nitrate ion (NO₃⁻)
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