Which is distilled first?

Which property among the following is the same for both hydrogen and deuterium molecules?

Hydrogen can be obtained from water,by the action of water on

Number of nucleons in $D_2$ molecule is

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

Identify the correct statements from the following.
$(i)$ $Zn$ reacts with dilute $HCl$ and aqueous $NaOH$ solution separately and liberates hydrogen.
$(ii)$ $Ti$ and $Zr$ form interstitial hydrides.
$(iii)$ The viscosity of $H_2 O$ is more than the viscosity of $D_2 O$.