Complete and balace the following chemical reaction:
(i). `Na_2CO_3` is added to a solution of copper sulphate.
`CuSO_4+Na_2O_3+H_2Oto…+Na_2SO_4`….
(ii). Potassium dichromate and concentrated HCl are heated together.
`K_2Cr_2O_7+"HCl"toKCl+.....+.....+....H_2O`
(iii). Copper reacts with `HNO_3` to give NO and `NO_2` in molar ratio of `2:1`
`Cu+HNO_3to...+NO+NO_2+`.....

Explanation

Let's solve the given reactions step by step.

### (i) Reaction of `Na2CO3` with `CuSO4`

1. **Write the reactants**: We have copper sulfate (`CuSO4`) and sodium carbonate (`Na2CO3`).

\[
CuSO_4 + Na_2CO_3
...