Balance the following chemical equation: `AgNO3+Cu rarr Cu(NO3)2+Ag`

Explanation

(i) `3MnO_4^(-) + 4H^(+) to MnO_2 + 2MnO_4 + 2H_2O`
(ii) `3SO_2 + Cr_2O_7^(2-) + 2H^(+) to Cr_2(SO_4)_3 + H_2O`