Question

Percentage of $Al$ in Aluminium carbide is 75% and in Aluminium oxide is 52.9%. If $C{O}_2$ has 27.27% carbon then the data illustrates:

• A. Law of multiple proportion
• B. Law of constant proportion
• C. Law of variable proportion
• D. Law of reciprocal proportion

Answer 1

The correct option is D Law of reciprocal proportion

Aluminium carbide contains $75\%$ of $Al$ and $25\%$ of $C$.

So, $3g$ of $Al$ combines with $1g$ of $C.$

Or ration $Al:C=3:1.$

Aluminium oxide contains $52\%$ of $Al$ and $47.1\%$ of $O.$

So, ratio $Al:O=52.9:47.1\equiv 1.123:1$

Or, $Al:O=3:261$

Ratio of $C:O=27.27:72.73=1:2.667$

So, carbon and oxygen combine in the same ratio as they reacted with $Al.$

$\therefore$ It shows the law of reciprocal proporation.