Which metal is used to make alloy steel for armour plates,safes and helmets?

Transition elements exhibit variable valencies because they release electrons from the following orbits:

Match the following:

List-$I$	List-$II$
$A$. Titanium	$I$. Non-metal
$B$. Fluorine	$II$. Transition metal
$C$. Tellurium	$III$. Lanthanoid
$D$. Dysprosium	$IV$. Metalloid

'Spin only' magnetic moment is same for which of the following ions?
$A$. $Ti^{3+}$ $B$. $Cr^{2+}$ $C$. $Mn^{2+}$ $D$. $Fe^{2+}$ $E$. $Sc^{3+}$
Choose the most appropriate answer from the options given below.

Which pair of compounds is expected to show similar colour in aqueous medium?

The electronic configuration of $Gd^{2+}$ is (at. no. of $Gd$ is $64$)