The electronic configuration of $Pt$ (atomic number $78$) is $...$

How many of the following metal ions have similar values of spin-only magnetic moment in the gaseous state?
(Given: Atomic number: $V, 23; Cr, 24; Fe, 26; Ni, 28$)
$V^{3+}, Cr^{3+}, Fe^{2+}, Ni^{3+}$

Which block element from the following are known as transition elements?

The atomic radius of $Ag$ is closest to

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

Which of the following properties is not expected to be shown by copper?