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AIIMS 2001
Exam
AIIMS
Year
2001
Subject
Chemistry
Chapter
Structure of Atom

AIIMS 2001 · Chemistry · Structure of Atom

Assertion : Ionisation potential of B (atomic no.5) is less than Be...

Assertion : Ionisation potential of B (atomic no.5) is less than Be (atomic no. 4). Reason : The first electron released from Be is of pp-orbital but that from B is of ss-orbital.

Options

  1. AIf both Assertion and Reason are true and Reason is the correct explanation of Assertion.
  2. BIf both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
  3. CIf Assertion is true but Reason is false.
  4. DIf Assertion is false but Reason is true.

Correct answer

C. If Assertion is true but Reason is false.

Step-by-step solution

Electronic configuration of berylium and boron is given as : Be⁡(Z=4):1s2,2s2B⁡(Z=5):1s2,2s2,2p1\begin{aligned}& \operatorname{Be}(Z=4): 1 s², 2 s² \\ & \operatorname{B}(Z=5): 1 s², 2 s², 2 p¹ \end{aligned}Ionisation potentialofBeof \mathrm{Be} is greater than that of boron as first electron released from BeB e is from ss-orbital while it is from $p-orbital in boron.
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