Solved: CHEMISTRY Question for NEET

NEET CHEMISTRYEasy

Which among the following has the maximum number of molecules?

7 g N₂

2 g H₂

16 g NO₂

16 g O₂

Identify the Principle: The number of molecules is directly proportional to the number of moles ( $n$ ). The formula to calculate moles is: $n = \frac{\text{Given Mass (g)}}{\text{Molar Mass (g/mol)}}$ [Class 12 Chemistry, Ch 1, Example 1.1]
Calculate moles for each option:

Option A ( $7\text{ g N}_2$ ): Molar mass of $N_2 = 2 \times 14 = 28\text{ g/mol}$ . $n = \frac{7}{28} = 0.25\text{ mol}$
Option B ( $2\text{ g H}_2$ ): Molar mass of $H_2 = 2 \times 1 = 2\text{ g/mol}$ . $n = \frac{2}{2} = 1.0\text{ mol}$
Option C ( $16\text{ g NO}_2$ ): Molar mass of $NO_2 = 14 + (2 \times 16) = 46\text{ g/mol}$ . $n = \frac{16}{46} \approx 0.35\text{ mol}$
Option D ( $16\text{ g O}_2$ ): Molar mass of $O_2 = 2 \times 16 = 32\text{ g/mol}$ . $n = \frac{16}{32} = 0.5\text{ mol}$

Conclusion: Option B ( $2\text{ g H}_2$ ) has the highest number of moles ( $1.0\text{ mol}$ ), and thus the maximum number of molecules.

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