In 2 kg mixture of copper and aluminum, 30% is copper. How much aluminum powder should be added to the mixture so that the proportion of the copper becomes 20%?

Given, Weight of the mixture = 2kg = 2000 grams

Percentage of copper = 30%

$$=$$> Percentage of Aluminium = 70%

$$=$$> Weight of Aluminium = $$\frac{70}{100}\times2000=1400$$ grams

Let the weight of the Aluminium powder added = $$x$$

After the addition of Aluminium powder,

Percentage of copper = 20%

$$=$$> Percentage of Aluminium powder = 80%

According to the Problem,

$$1400+x=\frac{80}{100}\left(2000+x\right)$$

$$=$$> $$1400+x=\frac{4}{5}\left(2000+x\right)$$

$$=$$> $$7000+5x=8000+4x$$

$$=$$> $$x=1000$$ grams

$$\therefore\ $$Weight of the aluminium powder added to the mixture = 1000 grams

Hence, the correct answer is Option A