Periodic Classification and Periodic Properties 2 Question 19
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19. The first ionisation potential of $\mathrm{Na}, \mathrm{Mg}, \mathrm{Al}$ and $\mathrm{Si}$ are in the order
======= ####19. The first ionisation potential of $\mathrm{Na}, \mathrm{Mg}, \mathrm{Al}$ and $\mathrm{Si}$ are in the order
3e0f7ab6f6a50373c3f2dbda6ca2533482a77bed (a) $\mathrm{Na}<\mathrm{Mg}>\mathrm{Al}<\mathrm{Si}$
(b) $\mathrm{Na}>\mathrm{Mg}>\mathrm{Al}>\mathrm{Si}$
(c) $\mathrm{Na}<\mathrm{Mg}<\mathrm{Al}>\mathrm{Si}$
(d) $\mathrm{Na}>\mathrm{Mg}>\mathrm{Al}<\mathrm{Si}$
(1988, 1M)
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Answer:
Correct Answer: 19. (c)
Solution:
- Ionisation energy increases from left to right in a period. However, exception occur between group 2 and group 13 elements on account of stability of electronic configuration of valence shell.
$\Rightarrow$ The desired order is $\mathrm{Na}<\mathrm{Mg}>\mathrm{Al}<\mathrm{Si}$
