Which of the following is the correct sequence of atomic weights of the given elements?

Out of all the known elements,the number of transition elements is:

Ionisation enthalpies of $Ce$,$Pr$ and $Nd$ are higher than $Th$,$Pa$ and $U$. Why?

Which of the following represents the correct order of the given properties?

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$: The first ionization enthalpy of $3d$ series elements is more than that of group $2$ metals.
Reason $(R)$: In $3d$ series of elements,successive filling of $d$-orbitals takes place.
In the light of the above statements,choose the correct answer from the options given below:

Which of the following sets correctly represents the increase in the paramagnetic property of the ions?