Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Ionisation enthalpies of early actinoids are lower than for early lanthanoids.
Reason (R): Electrons are entering orbitals in actinoids which experience greater shielding from nuclear charge.
In the light of the above statements, choose the correct answer from the option given below: [2023]
(A) is true but (R) is false.
(A) is false but (R) is true.
Both (A) and (R) are true and (R) is the correct explanation of (A).
Both (A) and (R) are true but (R) is not the correct explanation of (A).
(3)
Early actinoids have low ionisation enthalpy than early lanthanoids because electrons have more effective shielding from nuclear charge than electrons.
The incorrect statement among the following is [2021]
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.
The reason for greater range of oxidation states in actinoids is attributed to [2017]
actinoid contraction
and levels having comparable energies
and levels being close in energies
the radioactive nature of actinoids.
(2)
Actinoids have a greater range of oxidation states due to comparable energies of and orbitals. Hence, all their electrons can take part in bond formation.
