The one that is $NOT$ suitable for the removal of permanent hardness of water is :

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

Polyphosphates are used as water softening agents because:

Temporary hardness of water can be removed by

Match the reactants in List-$I$ with the products in List-$II$.

List-$I$	List-$II$
$(a). H_2O + H_2S$	$(i). (H_3O^{+}, HS^{-})$
$(b). H_2O + N^{3-}$	$(ii). (NH_3, OH^{-})$
$(c). H_2O + SiCl_4$	$(iii). (OH^{-}, H_3S^{+})$
$(d). H_2O + F_2$	$(iv). (SiO_2, HCl)$
	$(v). (SiO_4^{4-}, Cl_2)$
	$(vi). (O_2, F^{-})$
	$(vii). (HF, OH^{-})$
	$(viii). (OH^{-}, NH_3)$

Observe the following statements:
$1.$ Heavy water is harmful for the growth of animals.
$2.$ Heavy water reacts with $Al_4C_3$ and forms $\text{deuterated acetylene}$.
$3.$ $BaCl_2 \cdot 2D_2O$ is an example of $\text{interstitial deuterate}$.
The correct statements are: