Question

The number of molecules present in 2.8 g of nitrogen is:

• A. \( 6.023 \times 10^{22} \)
• B. \( 6.023 \times 10^{21} \)
• C. \( 6.023 \times 10^{20} \)
• D. \( 6.023 \times 10^{23} \)

Hint:

To calculate the number of molecules, use the formula: \[ \text{Number of molecules} = \text{moles} \times 6.023 \times 10^{23} \] and adjust for the given mass and molar mass.

Answer 1

The Correct Option is B

To find the number of molecules, we use Avogadro’s number and the molar mass of nitrogen. - Molar mass of nitrogen \( N_2 \) is 28 g/mol. - The number of moles in 2.8 g of nitrogen is: \[ \text{Moles} = \frac{2.8 \, \text{g}}{28 \, \text{g/mol}} = 0.1 \, \text{mol} \] - The number of molecules in 1 mole is \( 6.023 \times 10^{23} \), so the number of molecules in 0.1 moles is: \[ \text{Number of molecules} = 0.1 \times 6.023 \times 10^{23} = 6.023 \times 10^{22} \] Thus, the correct answer is \( 6.023 \times 10^{21} \).