Which of the following is the correct order of ionisation energy?
(1) `Be^(+) gt Be` (2) `Be gt Be^(+)`
(3) `C gt Be` (4) `B gt Be`

Options

A. ii,iii
B. iii,iv
C. I,iii
D. None of these

Answer

C

Explanation

(i) Due to more effective nuclear charge in `Be^+` than Be. (iii) Across the period, atomic size decreases and nuclear change increases and thus valence shell electron (s) is/are tightly held by nucleus. So, ionisation energy of C is greater than Be.