sblock Elements 1 Question 24
24. Which of the following atoms has the highest first ionisation energy?
(2016 Main)
(a) Na
(b) K
(c) Sc
(d) Rb
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Answer:
Correct Answer: 24. (c)
Solution: Order of first ionisation energy is $\mathrm{Sc}>\mathrm{Na}>\mathrm{K}>\mathrm{Rb}$.
Due to poor shielding effect, removal of one electron from $4 s$ orbital is difficult as compared to $3 s$-orbital.
BETA
