Question

The electrons, identified by quantum numbers 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 order of increasing energy, from the lowest to highest, as

• A. (iv) < (ii) < (iii) < (i)
• B. (ii) < (iv) < (i) < (iii)
• C. (i) < (iii) < (ii) < (iv)
• D. (iii) < (i) < (iv) < (ii)

Answer 1

The correct option is A

(iv) < (ii) < (iii) < (i)

(i) n = 4, l = 1 $\Rightarrow$ 4p-orbital

(ii) n = 4, l = 0 $\Rightarrow$ 4s-orbital

(iii) n = 3, l = 2 $\Rightarrow$ 3d-orbital

(iv) n = 3, l = 1 $\Rightarrow$ 3p-orbital

According to Aufbau principle, energies of above mentioned orbitals are in the order of

(iv) 3p < (ii) 4s < (iii) 3d < (i) 4p