Question

The number of nitrogen atoms in $21$ g of nitrogen are:

(Molecular Weight of Nitrogen $=14$ g/mole)

• A. $0.75$$N_A$
• B. $1.5$$N_A$
• C. $21$$N_A$
• D. $14$$N_A$

Answer 1

Answer: (B)

$1.5$$N_A$

Number of moles of nitrogen $=\frac{21}{28}=0.75$
So, the number molecules of nitrogen $0.75N_A$
The number of atoms of nitrogen $\Rightarrow 2\times 0.75N_A=1.5N_A$