Question

The number of electrons in different shells of sodium(Atomic no. - 11) are :

• A. $2,9$
• B. $1,8,2$
• C. $2,8,1$
• D. $2,7,2$

Answer 1

The correct option is C $2,8,1$

Atomic number of sodium is 11.

Number of protons = number of electrons = 11

First shell can accommodate 2 electrons so $K=2$.

Second shell can accommodate maximum of 8 electrons so $L=8$

Now remaining 1 electron will be accommodated in M i.e 1

So the configuration is $2,8,1$