Ncert Exercises & Solutions

Given below are two statements:

Assertion (A):	Boron has a smaller first ionisation enthalpy than beryllium.
Reason (R):	The penetration of 2s electron to the nucleus is more than the 2p electron hence 2p electron is more shielded by the inner core of electrons than the 2s electrons.

1.	Both (A) and (R) are True and (R) is the correct explanation of (A).
2.	Both (A) and (R) are True but (R) is not the correct explanation of (A).
3.	(A) is True but (R) is False.
4.	(A) is False but (R) is True.