Question

Which of the following pairs of gases contain the same number of molecules at STP?

• A. $11$ grams of $C{O}_2$ and $14$ grams of $CO$
• B. $14$ grams of $C_2{H}_4$ and $16$ grams of $C{H}_4$
• C. $16$ grams of $O_2$ and $17$ grams of $H_{2}S$
• D. $4$ grams of $He$ and $4$ grams of $H_2$

Answer 1

The correct option is C $16$ grams of $O_2$ and $17$ grams of $H_{2}S$

Mole is the SI unit of measurement used to measure the number of things, usually atoms or molecules. One mole of something is equal to $6.02214078\times {10}^{23}$ of same things particles (Avogadro's number).

16 g of $O_2$ contain $\frac{16}{32}\times 6.022\times {10}^{23}=0.5\times 6.023\times {10}^{23}$ molecules

17 g of $H_{2}S$ contain $\frac{17}{34}\times 6.022\times {10}^{23}=0.5\times 6.023\times {10}^{23}$ molecules

16 gm $O_2$ of and 17 gm of $H_{2}S$ contain same number of molecules