Column - I	Column - II
A) s-block	1) Outer shell  ‘ns orbital’
B) p-block	2) Antepenultimate shell $(n-2)$f orbital
C) d-block	3) Outermost shell  ‘np orbital’.
D) f-block	4) Penultimate shell $(n-1)$d orbital

For $A\to P$: Elements in the last electrons enter into ‘s orbital’ of ns energy shell .members of this block lie on the extreme left of the periodic table. Outer shell ‘ns orbital’.

For $B\to R$: Elements in which p-orbital are being progressively filled ,this block is situated at the extreme right of the periodic table . Outermost shell is ‘np orbital’.

 For $C\to S$: Elements in which last electrons enters the d-block ,the last electron is added to the penultimate shell. Penultimate shell,$(n-1)$d orbital.

For $D\to Q$: in these elements the  last enters f-orbital  electron. Antepenultimate shell, $(n-2)$f orbital.