The catalytic activity of transition metals and their compounds is due to their

Cuprous ion is colourless,while cupric ion is coloured because

The maximum and minimum melting points of the first and second transition series elements,respectively,are obtained with $-$

Number of paramagnetic ions among the following $d$- and $f$-block metal ions is . . . . . . . $Mn^{2+}$, $Cu^{2+}$, $Zn^{2+}$, $Yb^{2+}$, $Sc^{3+}$, $La^{3+}$, $Gd^{3+}$, $Lu^{3+}$, $Ti^{4+}$, $Ce^{4+}$. (Atomic number of $Mn = 25$, $Cu = 29$, $Zn = 30$, $Yb = 70$, $Sc = 21$, $La = 57$, $Gd = 64$, $Lu = 71$, $Ti = 22$, $Ce = 58$)

Which of the following weighs less when weighed in a magnetic field?

What is the correct order of spin only magnetic moment (in $BM$) of $Mn^{2+}, Cr^{2+}$ and $V^{2+}$?