Iron sulphide is heated in air to form $A$,an oxide of sulphur. $A$ is dissolved in water to give an acid. The basicity of this acid is

The density of a liquid is $1.5 \, g/mL$. There are $50 \, drops$ in $5 \, mL$. The number of molecules in $1 \, drop$ is (molecular weight of liquid is $100$).

$3.0$ molal $NaOH$ solution has a density of $1.110 \, g/mL$. The molarity of the solution is

Which of the following contain the same number of atoms?
$A$. $2 \text{ g}$ of $O_2$ gas
$B$. $4 \text{ g}$ of $SO_2$ gas
$C$. $1400 \text{ mL}$ of $O_2$ at $STP$
$D$. $0.05 \text{ L}$ of $He$ at $STP$
$E$. $0.0625 \text{ mol}$ of $H_2$ gas
Choose the correct answer from the options given below:

If lattice enthalpy and hydration enthalpy of $KCl$ are $699 \ kJ \ mol^{-1}$ and $-681.8 \ kJ \ mol^{-1}$ respectively,what is the enthalpy of solution of $KCl$?

State whether the following statements are true or false:
$(i)$ The molarity of a $0.6 \ N$ aqueous solution of ${H_3PO_3}$ is $1.2 \ M$.
$(ii)$ $\text{Empirical formula} = n \times \text{Molecular formula}$.
$(iii)$ In ${Cl_2O}$,the weight of chlorine combining with $8 \ g$ of oxygen is $35.5 \ g$.