Question

Total number of electrons in $18mL$ $H_{2}O$ is $x{N}_a$, where $N_a$ is the Avogadro number. What is the value of $x$?

Answer 1

Volume of $H_{2}O=18mL$

$\therefore$ Mass of $H_{2}O=18\times 1g=18g$

Number of moles $=\frac{18}{18}=1$ mole

$\therefore$ No.of molecules in $18g$ $H_{2}O=N_a$

Now, $1$molecule of $H_{2}O$ has $10$ electrons.

$\therefore N_a$ molecules of $H_{2}O$ has $10\times N_a$ electrons $=6.023\times {10}^{24}$ electrons.

Thus, the value of $x$ is $10$.