Question

The general electronic configuration of f-
block elements is
(A) ns2np6 (n - 1)d0-1 (n − 2) f1–14
(B) ns(n − 1)d0-1 (n + 2) f1-14
(C) ns2nd0,19 f1-14
(D) ns2 (n − 1)d0,1 (n − 1) f1-14​

Answer 1

First if you see the configuration of f block elements so you see that first 57 elements in which have configuration is 5d and 6s so according aufbau principal

S. 0

P.1

D.2

F.3

So here 6s is 6 and 5d is 7 so 5d next filled orbital but when come to second element in which 4f filled so it's energy is also 7 so 4f and 5d also same energy but when you see that

5d 5+2 and 4f is 4+3 so according aufbau principal any elements having less amount of n value which filled first because value is same but it's n value different so…