Identify the product obtained in following reaction.

Which of the following molecule has bond order 2 ?

Identify rare earth element from following.

0.2 molal aqueous solution of KCl freezes at $-0.680^{\circ} \mathrm{C}$. Calculate van't Hoff factor for this solution. $\left(\mathrm{K}_{\mathrm{f}}=1.86 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}\right)$