AP EAMCET · Chemistry · Classification of Elements and Periodicity in Properties
Assertion (A)
The first ionisation energy of Be is greater than that of \(\mathrm{B}\).
Reason (R) \(2 p\) orbital has lower energy than \(2 s\) orbital.
- A Both \(\mathrm{A}\) and \(\mathrm{R}\) are true and \(\mathrm{R}\) is a correct explanation for \(\mathrm{A}\).
- B Both \(\mathrm{A}\) and \(\mathrm{R}\) are true but \(\mathrm{R}\) is not a correct explanation for \(\mathrm{A}\).
- C \(A\) is true but \(R\) is false.
- D \(A\) is false but \(R\) is true.
Answer & Solution
Correct Answer
(C) \(A\) is true but \(R\) is false.
Step-by-step Solution
Detailed explanation
The first IE of Be is greater than that of B because Be has stable complete electronic configuration \(\left(1 s^2 2 s^2\right)\), which require more energy to remove the first electron from its valence shell, whereas, B has electronic configuration \(1 s^2 2 s^2 3 s^1\) which…
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