Ncert Exercises & Solutions

5.13 Calculate the total number of electrons present in 1.4 g of dinitrogen gas.

Molar mass of dinitrogen, N₂ = 28g mol^-1

Thus, 1.4 g of N₂ =

\frac{1.4}{28}

= 0.05 mol

= 0.05

\times

6.02

\times

10²³ number of molecules

= 3.01

\times

10^{23}

number of molecules

Now, 1 molecule of N₂ contains 14 electrons

Therefore, 3.01

\times

10²³ molecules of N₂ contains = 14

\times

3.01

\times

10²³

= 4.214

\times

10²³ electrons.