State the reason for the stability of the $Gd^{3+}$ ion.

Why do the transition elements exhibit variable oxidation states?

Consider $n$ as the number of lone pairs of electrons present in the equatorial position of the most stable structure of $ClF_3$. The ions from the following with $n$ number of unpaired electrons are :
$A. V^{3+}$
$B. Ti^{3+}$
$C. Cu^{2+}$
$D. Ni^{2+}$
$E. Ti^{2+}$
Choose the correct answer from the options given below :

Which of the following paramagnetic ions would exhibit a magnetic moment (spin only) of the order of $5 \ BM$?
(At. Nos. $Mn = 25$,$Cr = 24$,$V = 23$,$Ti = 22$)

The outermost shell electronic configuration of a transition element is:

Mercury is a liquid metal because .....