1. The electron in orbit dx2−y2 are present in x and y axis. So, electron density is not zero. 2. Higher the value of (n+l) higher will be the energy.For 3p n+l=3+1 =4 For2p n+l=2+1 =3 Thus, 3p has higher energy than 2p 3. The number of angular nodes is determined by the quantum number. 4. 4f -orbital have n=4 and l=3 and the number of radial nodesisn−l−1=4−3−1 =0