Question

The percentage of pure aluminium in $10kg$ of aluminum oxide ${AI}_2{O}_3$ of $90\%$ purity is $47.64\%$.
[AI=27, O=16]

• A. True
• B. False

Answer 1

The correct option is A True

Solution:- (A) True

Molecular weight of ${Al}_2{O}_3=102g$

Molecular weight of $Al=27g$

Weight of $Al$ in ${Al}_2{O}_3=2\times 27=54g$

As given that the given sample of ${Al}_2{O}_3$ is $90\%$ pure, i.e., $10Kg$ of sample has $9Kg$ of pure ${Al}_2{O}_3$.

Therefore,

Amount of $Al$ in $102g$ of ${Al}_2{O}_3=54g$

Amount of $Al$ in $9000g$ of ${Al}_2{O}_3=\frac{54}{102}\times 9000=4764.7g$

Total weight of sample $=10Kg=10000g$

$\therefore$ percentage of $Al$ in given sample $=\frac{4764.7}{10000}\times 100=47.64\%$

Hence the given statement is true.