Periodic Classification and Periodic Properties - Result Question 14
11. Which of the following represents the correct order of increasing first ionisation enthalpy for $Ca, Ba, S$, Se and $Ar$ ?
(a) $Ca < S < Ba < Se < Ar$
(b) S $ < $ Se $ < Ca < Ba < Ar$
(c) $Ba < Ca < Se < $ S $ < Ar$
(d) $Ca < Ba < S < Se < Ar$
(2013 Main)
Show Answer
Answer:
Correct Answer: 11. (c)
Solution:
- Ionisation energy increases along a period from left to right and decreases down a group. The position of given elements in the periodic table is as
| Group No. 2 | $\mathbf{1 6}$ | $\mathbf{1 8}$ |
|---|---|---|
| $Ca$ | $S$ | $Ar$ |
| $Ba$ | $Se$ |
Thus, the order of increasing $\Delta H _{IE _1}$ is $Ba < Ca < Se < S < Ar$
BETA
