The equilibrium

$$2C{u^+} \to Cu^\circ + C{u^{2+}}$$

In aqueous medium at 25$$^\circ$$C shifts towards the left in the presence of

The correct functional group X and the reagent/reaction condition Y in the following scheme are

Reduction of the metal centre in aqueous permanganate ion involves

The total number of contributing structure showing hyper-conjugation (involving C-H bonds) for the following carbocation is _________.