Question

Given below are two statements:

Statement I: Both ${\mathrm{CaCl}}_2.6{\mathrm{H}}_2\mathrm{O}$ and ${\mathrm{MgCl}}_2.8{\mathrm{H}}_2\mathrm{O}$ undergo dehydration on heating.

Statement II: $\mathrm{BeO}$ is amphoteric whereas the oxides of other elements in the same group are acidic.

• A. Statement I is true but statement II is false
• B. Both Statement I and Statement II are false
• C. Statement I is false but statement II is true
• D. Both Statement I and Statement II are true

Answer 1

The correct option is B

Both Statement I and Statement II are false

Solution:

• For statement I: On heating, hydrated calcium chloride will convert into anhydrous calcium chloride, but heating of hydrated magnesium chloride will lead to the formation of magnesium oxide instead of anhydrous magnesium chloride.

Therefore, the statement I is incorrect.

${\mathrm{CaCl}}_2.6{\mathrm{H}}_2\mathrm{O}\to {\mathrm{CaCl}}_2+6{\mathrm{H}}_2\mathrm{O}$

${\mathrm{MgCl}}_2.8{\mathrm{H}}_2\mathrm{O}\to \mathrm{MgO}+{\mathrm{Cl}}_2+6{\mathrm{H}}_2\mathrm{O}$

• For statement II: Among alkaline earth metals, $\mathrm{BeO}$ is amphoteric, and the rest are basic oxides because on reaction with water they form metal hydroxide which turns red litmus blue. It has diagonal relationship with aluminium.

Therefore, statement II is incorrect.

For example: ${\mathrm{MgCl}}_2.6{\mathrm{H}}_2\mathrm{O}\to \mathrm{MgCl}\left(\mathrm{OH}\right)+\mathrm{HCl}+5{\mathrm{H}}_2\mathrm{O}$

So, the correct option is B.