The correct order of decomposition temperature of $MgCO_3$ $(X)$,$BaCO_3$ $(Y)$,$CaCO_3$ $(Z)$ is

Reaction of $BeCl_{2}$ with $LiAlH_{4}$ gives.
$(A)$ $AlCl_{3}$; $(B)$ $BeH_{2}$; $(C)$ $LiH$; $(D)$ $LiCl$; $(E)$ $BeAlH_{4}$
Choose the correct answer from options given below.

The hydration energy of $Mg^{2+}$ ions is lesser than that of

Which of the following is a pair of amphoteric hydroxides?

Which of the following elements can be represented by the electronic configuration $[Kr]\,5s^2$?

The product obtained on fusion of $BaSO_4$ and $Na_2CO_3$ is