Periodic Classification and Periodic Properties 2 Question 15
15. The incorrect statement among the following. (1997(C), 1M)
(a) The first ionisation potential of $\mathrm{Al}$ is less than the first ionisation potential of $\mathrm{Mg}$
(b) The second ionisation potential of $\mathrm{Mg}$ is greater than the second ionisation potential of $\mathrm{Na}$
(c) The first ionisation potential of $\mathrm{Na}$ is less than the first ionisation potential of $\mathrm{Mg}$
(d) The third ionisation potential of $\mathrm{Mg}$ is greater than third ionisation potential of $\mathrm{Na}$
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Answer:
Correct Answer: 15. (b)
Solution:
- (a) Correct statement In a period, element of 2nd group has higher first ionisation potential than element of group 13.
(b) Incorrect statement $\mathrm{Mg}^{+}$require less energy for further ionisation than $\mathrm{Na}^{+}$because of noble gas configuration of $\mathrm{Na}^{+}$.
(c) Correct statement Ionisation energy increases from left to right in a period.
