The charring of sugar takes place when treated with concentrated $H_2SO_4$. What is the type of reaction involved in it?

Which of the following is not considered hard water?

Which physical constant for $H_2O$ has a higher magnitude than $D_2O$?

What is $X$ in the following reaction?
$MgCl_2 + 2H_2O \to X + 2HCl + H_2O$

Temporary hardness may be removed from water by adding

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?