All reactions which involve chemical disintegration are:

The number of moles of solute present in the solutions of $I$,$II$ and $III$ is respectively:
$I$. $500 \ mL$ of $0.2 \ M \ NaOH$
$II$. $200 \ mL$ of $0.1 \ N \ H_2SO_4$
$III$. $6 \ g$ of urea in $1 \ kg$ of water

The volume of $HCl$,containing $73 \ g \ L^{-1}$,required to completely neutralize $NaOH$ obtained by reacting $0.69 \ g$ of metallic sodium with water,is $........ mL$. (Nearest Integer) (Given: molar masses of $Na, Cl, O, H$ are $23, 35.5, 16$ and $1 \ g \ mol^{-1}$ respectively)

Assign $A, B, C, D$ from the given type of reaction.
$CaCl_2 + Na_2SO_4 \longrightarrow $ No reaction

What are the different elements present in the mineral barite?

Arrange the following in the order of increasing mass (atomic mass: $O = 16, Cu = 63, N = 14$)
$I.$ one atom of oxygen
$II.$ one atom of nitrogen
$III.$ $1 \times 10^{-10}$ mole of oxygen
$IV.$ $1 \times 10^{-10}$ mole of copper