Transition and InnerTransition Elements - Result Question 3
3. The correct order of the first ionisation enthalpies is
(2019 Main, 10 April II)
(a) $Mn< Ti< Zn < Ni$
(b) $Ti< Mn < Zn < Ni$
(c) $Zn< Ni < Mn < Ti$
(d) $Ti < Mn < Ni < Zn$
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Answer:
Correct Answer: 3. (d)
Solution:
The $3 d$-transition series is
In 1st ionisation, one electron will be removed from $4 s^2$ subshell/orbital.
With increase in atomic number $(Z)$, i.e. with increase in number of protons in the nucleus, effective nuclear charge $\left(Z^*\right)$ also increases from Sc to Zn .
$$ \mathrm{IE} \propto Z^* $$
So, IE order of the given elements will be,
$$ \mathrm{Ti}<\mathrm{Mn}<\mathrm{Ni}<\mathrm{Zn} $$
BETA
