An element reacts with hydrogen to form a compound $A$,which on treatment with water liberates hydrogen gas. The element can be

All of the following substances react with water. Which of the following pairs will produce the same gaseous product upon reaction with water?

Lime reacts exothermally with water to give '$A$' which has low solubility in water. Aqueous solution of '$A$' is often used for the test of $CO_{2}$,a test in which insoluble $B$ is formed. If $B$ is further reacted with $CO_{2}$ then a soluble compound is formed. '$A$' is

Solubility of sulphates of group $2$ elements decreases down the group due to

Given below are two statements:
Statement $I$: Both $CaCl_2 \cdot 6H_2O$ and $MgCl_2 \cdot 8H_2O$ undergo dehydration on heating.
Statement $II$: $BeO$ is amphoteric whereas the oxides of other elements in the same group are acidic.
In the light of the above statements,choose the correct answer from the options given below:

Which of the following compounds has a lattice energy value lower than its hydration energy?