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 calculate the number of molecules, we utilize Avogadro’s number and the molar mass of nitrogen. - The molar mass of nitrogen (\( N_2 \)) is 28 g/mol. - The moles of nitrogen in 2.8 g is determined as follows: \[ \text{Moles} = \frac{2.8 \, \text{g}}{28 \, \text{g/mol}} = 0.1 \, \text{mol} \] - Knowing that 1 mole contains \( 6.023 \times 10^{23} \) molecules, the number of molecules in 0.1 moles is: \[ \text{Number of molecules} = 0.1 \times 6.023 \times 10^{23} = 6.023 \times 10^{22} \] Therefore, the answer is \( 6.023 \times 10^{21} \).