The mass of zinc produced by the electrolysis of zinc sulphate solution with a steady current of $$0.015$$ A for $$15$$ minutes is _______ $$\times 10^{-4}$$ g. (Atomic mass of zinc $$= 65.4$$ amu)

$$Q = It = 0.015 \times 15 \times 60 = 13.5$$ C.

Moles of electrons = $$13.5/96500$$.

Zn²⁺ + 2e⁻ → Zn. Moles of Zn = $$13.5/(2 \times 96500) = 6.994 \times 10^{-5}$$.

Mass = $$6.994 \times 10^{-5} \times 65.4 = 45.74 \times 10^{-4} \approx 46 \times 10^{-4}$$ g.

The answer is $$\boxed{46}$$.