Verified Solution • 2025–26 Session
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QNEET-2021-Ch-580: NEET 2021 Chemistry - Class 12 NEET-2021-Ch-580 Solution: The incorrect statement among the following is: Actinoids are…
The incorrect statement among the following is: Actinoids are highly reactive metals especially when finely divided. Actinoid contraction is greater for element to element than lanthanoid contraction. Most of the trivalent Lanthanoid ions are colorless in the solid state. Lanthanoids are good conductors of heat and electricity.
Multiple Choice Options
- A Actinoids are highly reactive metals, especially when finely divided.
- B Actinoid contraction is greater for element to element than lanthanoid contraction.
- C Most of the trivalent Lanthanoid ions are colorless in the solid state.
- D Lanthanoids are good conductors of heat and electricity.
Step-by-Step Verified Solution
_ The surface area increases when
actinoids are finely divided which results
in exposure of more reactant molecules
to react. Hence, rate increases and so,
actinoids are highly reactive metals
when finely divided.
_ The shielding effect of 5f-orbitals in
actinoids is poor than the shielding
effect of4f-orbitals. So, the effective
nuclear charge on valence electrons is
more in actinoids. Hence, actinoid
contraction is greater than lanthanoid
contraction.
_ Trivalent lanthanoid ions are coloured in
the solid state due to presence of
f-electrons.
_ Lanthanoids are inner transition metals.
So, they are good conductors of heat
and electricity.