Question

The number of N atoms in $681\ g$ of $C_7H_5N_3O_6$ is $x × 10^{21}$. The value of $x$ is ______ . ($N_A$ = $6.02 × 10^{23}\ mol^{–1}$) (Nearest Integer)

Answer 1

Molar mass of $C_7H_5N_3O_6 = 227\ g/mol$
$681\ g$ of $C_7H_5N_3O_6$ = $3$ mol
∴ $681\ g$ of $C_7H_5N_3O_6$ has $9$ mole of N.
= $54.18 × 10^{23}$ N atoms
= $5418 × 10^{21}$

So, the answer is $5418$.