The decrease in atomic volume from $Cr$ to $Cu$ in the $3d$ series is very negligible because:

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

The correct order of the following $3d$ metal oxides,according to their oxidation numbers is:
$(a)$ $CrO_3$ $(b)$ $Fe_2O_3$ $(c)$ $MnO_2$ $(d)$ $V_2O_5$ $(e)$ $Cu_2O$

Which of the following is ferromagnetic?

Which of the following has the maximum number of unpaired electrons?