The electrons, identified by quantum number n and l
i. `n = 4,l=1` ii. `n = 4, l= 0` iii. `n = 3 , l= 2 ` iv. `n= 3 , l = 1`
can be placed in the order of increasing energy from the lowest to highest, which is

Options

A. `(iv) lt (ii) lt (iii) lt (i)`
B. `(ii) lt (iv) lt (i) lt (iii)`
C. `(i) lt (iii) lt (ii) lt (iv)`
D. `(iii) lt (i) lt (iv) lt (ii)`

Answer

A

Explanation

(a) The two guiding rules to arrange the various orbitals in the increasing energy are :
(i) Energy of an orbital increases with increase in the value of `n + 1`
(ii) Of orbitals having the same value of `n +1`, the orbital with lower value of `n` has lower energy.
Thus for the given orbitals, we have
(i) `n + 1 = 4 + 1 = 5`
(ii) `n + 1 = 4 + 0 = 4`
(iii) `n + 1 = 3 + 2 = 5`
(iv) `n + 1 = 3 + 1 = 4`
Hence, the order of increasing energy is.
`(iv) lt (ii) lt (iii) lt (i)`.