Which of the following statements related to lanthanoids is incorrect?

Which of the following elements belongs to the actinide series?

Determine whether the following statements are True $(T)$ or False $(F)$:
$(a)$ Actinoid contraction is greater than lanthanoid contraction.
$(b)$ Actinoids are elements of the $4f$ series.
$(c)$ All actinoid elements have a $7s^2$ configuration.

The element californium belongs to the family of

What are the formulae of the compounds formed when lanthanoids $(Ln)$ react with nitrogen and halogen respectively?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: $5f$ electrons can participate in bonding to a far greater extent than $4f$ electrons.
Reason $R$: $5f$ orbitals are not as buried as $4f$ orbitals.
In the light of the above statements,choose the correct answer from the options given below: