The quantum numbers +1/2 and -1/2 for the electron spin represent

The number of nodal planes in a p_x orbital is

The electronic configuration of an element is 1s², 2s² 2p⁶, 3s² 3p⁶ 3d⁵, 4s¹ This represents its

The electrons, identified by quantum numbers n and l, (i) n = 4, l = 1, (ii) n = 4, l = 0, (iii) n = 3, l = 2 and (iv) n = 3, l = 1 can be placed in order of increasing energy, from the lowest to highest, as