How many nodes are there in 3s-orbital?

Explanation

The spherical shell (or region) inside s-orbital where electron density is zero is called the node. In case of 3s-orbital, there are two such spherical shell where the electron density is zero. So 3s-orbital has two radial nodes but no angular node (l=0). so total no. of nodes is 2. [No. of nodal surface=n-1, where n is the principal quantum number].