Question

Which shows exothermic dissolution?

• A. $KN{O}_3$
• B. $KBr$
• C. $NaCl$
• D. $Ca{\left(OH\right)}_2$

Answer 1

Answer: (D)

$Ca{\left(OH\right)}_2$

$Ca(OH{)}_2$ shows exothermic dissolution.
$Ca\left(OH{)}_2\right(s\left)\underset{H_{2}O}{\rightleftharpoons }Ca\right(OH{)}_2\left(aq\right)+\Delta H$
When the temperature is raised, the heat is supplied and the equilibrium is shifted towards left. Thus the solubility decreases. This is also observed from graph which shows higher solubility at lower temperature and lower solubility at higher temperature for $Ca(OH{)}_2$.