Directions for: The questions consist of two statements each, printed as assertion and reason. While answering these questions you are required to choose any one of the following five responses A. If both the Assertion and the Reason are true and the Reason is a correct explanation of the Assertion. B. If both the Assertion and the Reason are true but the Reason is not a correct explanation of Assertion. C. If the Assertion is true but the Reason is false. D. If both the Assertion and the Reason are false. E. If Assertion is false but Reason is true.
Assertion: The first ionisation energy of Be is greater than boron. Reason: 2p orbitals have lower energy than 25 orbitals.A) A
B) B
C) C
D) D
E) E
Correct Answer: C
Solution :
Ionization energy increase in a period from left to right due to decrease in size. But it is observed that IE of IIA > IIIA because of higher stability of elements of IIA group due to completely filled S orbital. Note: Completely filled and half-filled orbitals are more stable than incompletely filled orbitals thus large amount of energy is required to remove the electrons). Thus IE of Be is more than B. But 2p orbital is more than 2s orbital.
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