What happens when Gold is treated with Concentrated Nitric acid?

Explanation

During MPV reduction of aldehyde or (RCH=O) or `(R_(2)C=O)` to `(R underset(H_(a))underset(|)(CH)-OH_(b))` or `(R_(2) underset(H_(a))underset(|)(C)-OH_(b))`, the `H_(a)` atom is supplied by alpha-CH bond of the alkoxide and the H_(b) atom is supplied by the (OH) group of the solvent

It does not reduce (C=C) and (C = C) bonds.