Question

Arrange the following in decreasing order of the number of molecules contained in: (A) 16 g of O$_2$, (B) 16 g of CO$_2$, (C) 16 g of CO, (D) 16 g of H$_2$

• A. (A), (B), (C), (D)
• B. (D), (C), (A), (B)
• C. (B), (A), (D), (C)
• D. (C), (B), (D), (A)

Answer 1

The Correct Option is B

\(\text{To compare the number of molecules, use the formula:} \\ \text{Number of moles} = \frac{\text{mass}}{\text{molar mass}} \\ - \, \text{O}_2 \text{ has a molar mass of } 32 \, \text{g/mol, so moles of O}_2 = \frac{16}{32} = 0.5 \, \text{moles}. \\ - \, \text{CO}_2 \text{ has a molar mass of } 44 \, \text{g/mol, so moles of CO}_2 = \frac{16}{44} \approx 0.36 \, \text{moles}. \\ - \, \text{CO} \text{ has a molar mass of } 28 \, \text{g/mol, so moles of CO} = \frac{16}{28} \approx 0.57 \, \text{moles}. \\ - \, \text{H}_2 \text{ has a molar mass of } 2 \, \text{g/mol, so moles of H}_2 = \frac{16}{2} = 8 \, \text{moles}. \\ \text{Thus, the decreasing order is } \text{H}_2 > \text{CO} > \text{O}_2 > \text{CO}_2.\)