The $d$-block elements consist mostly of

Elements $A$ and $B$ with their respective electronic configurations $3d^{10} 4s^1$ and $4d^{10} 5s^1$ in their outermost shell are

Fill in the blanks:
$(a)$ The ground state electronic configurations of $Cr$ and $Cu$ are .......... and ..........,respectively.
$(b)$ Transition elements exhibit certain characteristic properties due to partially filled $d$-orbitals.
$(c)$ The general electronic configuration of transition elements is .......... .

The correct order of the first ionization enthalpies is:

Which of the following statements is correct?

Although Zirconium belongs to the $4d$ transition series and Hafnium to the $5d$ transition series,they show similar physical and chemical properties because . . . . . . .