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

Which of the following ions will exhibit colour in aqueous solution?

The melting point of $Zn$ is lower as compared to those of the other elements of the $3d$ series because:

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 elements has the maximum density?

Which of the following sets of elements does not possess $f$-electrons?