The number of atoms in $4.25$ $\mathrm{g}$ of ${\mathrm{NH}}_3$ is  $\times {10}^{23}$.  $(6.022, 7.022, 9.022)$

The mass of one hydrogen atom is _____.

$$\begin{gathered} \mathrm{A}: 1.67\times {10}^{-24} \mathrm{g} \\ \mathrm{B}: 1.67\times {10}^{-14} \mathrm{g} \\ \mathrm{C}: 1.67\times {10}^{-34} \mathrm{g} \end{gathered}$$

(Enter your correct answer as $\mathrm{A}, \mathrm{B} \mathrm{or} \mathrm{C}$)

One mole of ${\mathrm{CO}}_2$ contains _____ $\times {10}^{23}$ atoms of carbon. $( 5.02, 6.02, 7.02)$ 

(Write the answer upto two decimal places.)

The number of atoms present in $10$ $\mathrm{g}$ of calcium is _____ $\times {10}^{23}$ atoms.

(Write the answer upto one decimal value.)