MHTCET 14 May 2023 Shift 2 Solved Paper

The Law of Multiple Proportions states that when two elements form more than one compound, the masses of one element that combine with a fixed mass of the other element are in the ratio of small whole numbers. To identify which pair of compounds demonstrates the law of multiple proportions, let's analyze each option:Option A: $\mathrm{CH}_4, \mathrm{CCl}_4$This pair does not demonstrate the law of multiple proportions, as the compounds have different elements (hydrogen in $\mathrm{CH}_4$ and chlorine in $\mathrm{CCl}_4$ ) combining with carbon, without a fixed mass of one element combining with varying masses of the other.Option $\mathrm{B}: \mathrm{BF}_3, \mathrm{NH}_3$This option is also not an example of the law of multiple proportions, as these compounds do not contain the same two elements combining in different ratios; $\mathrm{BF}_3$ contains boron and fluorine whereas $\mathrm{NH}_3$ contains nitrogen and hydrogen. Option $\mathrm{C}: \mathrm{CO}, \mathrm{CO}_2$This option correctly represents the law of multiple proportions. Both $\mathrm{CO}$ and $\mathrm{CO}_2$ consist of carbon and oxygen. In carbon monoxide $(\mathrm{CO})$, one atom of carbon combines with one atom of oxygen, whereas in carbon dioxide $(\mathrm{CO}_2)$, one atom of carbon combines with two atoms of oxygen. Here, the fixed mass of carbon combines with varying masses of oxygen in a ratio of 1:2 (for the oxygen atoms).Option D: $\mathrm{NO}_2, \mathrm{CO}_2$Like Option A and B, this choice does not follow the law of multiple proportions because each compound has different elements combining with each other; $\mathrm{NO}_2$ has nitrogen and oxygen, while $\mathrm{CO}_2$ has carbon and oxygen.The correct answer is therefore Option $\mathrm{C}$ : $\mathrm{CO}, \mathrm{CO}_2$, as these two compounds consist of the same two elements, carbon and oxygen, which combine in different simple numerical ratios, fulfilling the criteria of the law of multiple proportions.