Which of the following methods is used for the removal of temporary hardness of water?

Which of the following compounds is used for the softening of hard water by Clark's method?

Match List-$I$ with List-$II$ and select the correct answer using the codes given below.

List-$I$	List-$II$
$1.$ Heavy water	$(a)$ Bicarbonates of $Ca$ and $Mg$ in water
$2.$ Temporary hard water	$(b)$ No foreign ions in water
$3.$ Soft water	$(c)$ $D_2O$
$4.$ Permanent hard water	$(d)$ Sulphates and chlorides of $Ca$ and $Mg$ in water

Water is oxidised to oxygen by

The numbers of protons,electrons and neutrons in a molecule of heavy water are respectively

Find the number of $CORRECT$ order against mentioned property :-
$(i)$ $D_2O = H_2O$ (number of electrons)
$(ii)$ $D_2O > H_2O$ $(|\Delta H_f|)$
$(iii)$ $D_2O > H_2O$ $(|\Delta H_{vaporization}|)$
$(iv)$ $D_2O > H_2O$ (density)
$(v)$ $D_2O > H_2O$ (Molecular mass)