An alloy contains 32% copper, 24% nickel and rest zinc. How much zinc is present in 12 kg of the alloy?

The alloy is composed of three metals whose percentage by mass must add up to $$100\%$$.

Given: copper = $$32\%$$, nickel = $$24\%$$.
Therefore, percentage of zinc = $$100\% - (32\% + 24\%) = 100\% - 56\% = 44\%$$.

The total mass of the alloy is $$12 \text{ kg}$$. The mass of zinc is obtained by taking $$44\%$$ of this total mass.

Mass of zinc $$= \frac{44}{100} \times 12 \text{ kg} = 0.44 \times 12 \text{ kg}$$.

Calculating the product: $$0.44 \times 12 = 5.28$$.

Hence, the amount of zinc present in the 12 kg alloy is $$5.28 \text{ kg}$$.

Option D which is: 5.28 kg