How many moles of hydrogen gas \( \left(\mathrm{H}_{2}\right) \) would contain \( 2.4 \times 10^{24} \) hydrogen atoms? a 2 b 5 c 4 d 3

To find the number of moles of hydrogen gas (\(\mathrm{H}_{2}\)), first, let's remember that each molecule of hydrogen gas consists of 2 hydrogen atoms. Therefore, to convert atoms to molecules, divide the total number of hydrogen atoms by 2: \[ \text{Number of } \mathrm{H}_{2} \text{ molecules} = \frac{2.4 \times 10^{24} \text{ H atoms}}{2} = 1.2 \times 10^{24} \text{ H}_{2} \text{ molecules} \] Now, to find moles, use Avogadro’s number, \(6.022 \times 10^{23}\) molecules/mol: \[ \text{Moles of } \mathrm{H}_{2} = \frac{1.2 \times 10^{24} \text{ molecules}}{6.022 \times 10^{23} \text{ molecules/mol}} \approx 2.00 \text{ mol} \] So the answer is **a 2**. Molecular compounds have fascinating historical roots. For instance, hydrogen was the first element identified in the universe and was discovered by Henry Cavendish in 1766. The term "hydrogen" comes from the Greek words "hydro" (water) and "genes" (creator), essentially meaning "water producer" once it combines with oxygen. When dealing with mole conversions, a common mistake is confusing atoms and molecules. Remember, a molecule of \(\mathrm{H}_{2}\) has two hydrogen atoms. Whenever you see hydrogen gas, always keep in mind it is in diatomic form and adjust your calculations accordingly to avoid oversights!