Systematic name of $H_2O$ (oxide of hydrogen) is

When chlorine water is exposed to sunlight,$O_2$ is liberated. Hence

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

Which of the following statements is not true?

Which of the following properties is less for $D_2O$ than $H_2O$?

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?