A compound that releases CO₂ most easily upon heating is?
1. $K_{2}C{O}_3$
2. $N{a}_{2}C{O}_3$
3. $MgC{O}_3$
4. $CaC{O}_3$

 An active ingredient in bleaching powder that aids in the bleaching action is:

1.  $\mathrm{Ca}{\left(\mathrm{OCl}\right)}_2$

2.  ${\mathrm{CaO}}_2\mathrm{Cl}$

3.  ${\mathrm{CaCl}}_2$

4.  ${\mathrm{CaOCl}}_2$

A compound that has higher hydration enthalpy than the lattice enthalpy is: 

1. ${\mathrm{CaSO}}_4$

2. ${\mathrm{BeSO}}_4$

3. ${\mathrm{BaSO}}_4$

4. ${\mathrm{SrSO}}_4$