Temporary hardness and permanent hardness can be removed by the sequential addition of which of the following?

When temporary hard water containing $Mg(HCO_3)_2$ is boiled,the precipitate formed is of:

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:

The products obtained during the treatment of hard water using Clark's method are:

Some statements about heavy water are given below:
$(i)$ Heavy water is used as a moderator in nuclear reactors.
$(ii)$ Heavy water is more associated than ordinary water.
$(iii)$ Heavy water is more effective solvent than ordinary water.
Which of the above statements are correct?

Temporary hardness and permanent hardness can be removed by adding $........$ respectively.