Question

which subshell have (n+l) value is equal to 2​

Answer 1

The subshell with n=2 and l=1 is the 2psubshell; if n=3 and l=0, it is the 3ssubshell, and so on. The value of l alsohas a slight effect on the energy of thesubshell; the energy of the subshellincreases with l (s < p < d < f). 

The shell "K" has been given the value n = 1, the "L" shell has been given the value n = 2. ... When n = 2 there are two sets of subshells; l = 1 and l = 0.