The number of unpaired electrons in the ground state of $Cl$ atom $(atomicnumber=17)$ is:

The correct option is A 1
Unpaired electrons are the electrons in the outermost shell which are singly occupying the shell.

The electronic configuration of $Cl$ in its ground state = $1s^{2}2s^{2}2p^{6}3s^{2}3p^5$

So, in the orbital diagram of $3p$ orbital, Only 1 electron is unpaired in the ground state.

Hence, the number of unpaired electrons in $Cl$ is 1.