BITSAT 2017 Paper

For a given orbital with principal quantum number (n) and azimuthal quantum number (l)
number of radial nodes=(n−l−1)
for 3s orbital: n=3 and l=0
therefore, number of radial nodes=3−0−1=2
for 2p orbital: n=2 and l=1
therefore, number of radial nodes =2−1−1=0