NEETChemistryClassification of Elements and Periodicity in Properties
Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): The first ionization enthalpy of Boron is slightly less than that of Beryllium. Reason (R): The 2p electron of Boron is more penetrating towards the nucleus than the 2s electron of Beryllium. In the light of the above statements, choose the correct answer from the options given below:
Options
- ABoth (A) and (R) are true and (R) is the correct explanation of (A)
- BBoth (A) and (R) are true but (R) is not the correct explanation of (A)
- C(A) is true but (R) is false
- D(A) is false but (R) is true
Correct answer
C. (A) is true but (R) is false
Step-by-step solution
Assertion (A) is true because the first ionization enthalpy of Beryllium ( Be , 1s^2 2s^2 ) is higher than that of Boron ( B , 1s^2 2s^2 2p^1 ). Removing an electron from the fully filled, stable 2s orbital of Be requires more energy than removing the single 2p electron of B . Reason (R) is false because the penetration of a 2s electron to the nucleus is greater than that of a 2p electron. The 2p electron of Boron is more shielded from the nucleus by the inner core of electrons and is less penetrating compared to t