Question

If $N_A$ is Avogadro's number, then calculate the number of electrons in $4.2g$ of $N^{3-}$.

• A. $2.1N_A$
• B. $3N_A$
• C. $6N_A$
• D. $N_A$

Answer 1

Answer: (A)

$2.1N_A$

$N^{3-}$ contains 10 electrons.

Number of moles $=\frac{4.2}{14}$

$=0.3moles$

No of electrons in $0.3moles=0.3\times N_A\times 10$

$=3N_A$

Hence, option B is correct.