Question

1.0 g of H₂ has the same number of molecules as in:

• A. 14 g of N₂
• B. 18 g of H₂O
• C. 16 g of CO
• D. 28 g of N₂

Answer 1

The Correct Option is A

The number of moles (n) is calculated as $n = \frac{mass (g)}{molar mass (g/mol)}$. The quantity of molecules (N) is determined by $N = nN_A$, where $N_A$ represents Avogadro's number.
For 1.0 g of H$_2$: The molar mass of H$_2$ is 2.016 g/mol. Thus, the moles of H$_2$ are $\frac{1.0 g}{2.016 g/mol} \approx 0.496$ mol. The corresponding number of molecules is 0.496 $\times$ $N_A$.
Comparing this to the options:
(1) For 14 g of N$_2$: The molar mass of N$_2$ is 28 g/mol. The moles of N$_2$ are $\frac{14 g}{28 g/mol} = 0.5$ mol. The number of molecules is 0.5 $\times$ $N_A$.
Therefore, 14 g of N$_2$ contains a quantity of molecules approximately equal to that of 1 g of H$_2$.