A solid compound is formed by atoms of $A$ (cations), $B$ (cations) and O (anions). Atoms of O form hcp lattice. Atoms of $A$ occupy $25 \%$ of tetrahedral holes and atoms of $B$ occupy $50 \%$ octahedral holes. What is the molecular formula of solid?
The density of nitric acid solution is $1.5 \mathrm{~g} \mathrm{~mL}^{-1}$. Its weight percentage is 68 . What is the approximate concentration (in $\mathrm{mol} \mathrm{L}^{-1}$ ) of nitric acid ?
$$ (\mathrm{N}=14 \mathrm{u} ; \mathrm{O}=16 \mathrm{u} ; \mathrm{H}=1 \mathrm{u}) $$
The osmotic pressure of sea water is 1.05 atm . Four experiments were carried as shown in table. In which of the following experiments, pure water can be obtained in part-II of vessel.

Aqueous $\mathrm{CuSO}_4$ solution was electrolysed by passing 2 amp of current for 10 min . What is the weight (in g) of copper deposited at cathode ?
$$ \left(\mathrm{Cu}=63 \mathrm{u} ; F=96500 \mathrm{C} \mathrm{~mol}^{-1}\right) $$