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

If the density of methanol is $0.793 \, kg \, L^{-1}$,what is its volume needed for making $2.5 \, L$ of its $0.25 \, M$ solution (in $, mL$)?

If one liter of air is repeatedly passed over heated copper and magnesium until no further reduction in volume occurs,the final volume of the air will be approximately ......... $mL$.

$16 \ g$ each of $H_2$,$He$,and $O_2$ are present in a container exerting $10 \ atm$ pressure at $T \ (K)$. The pressure in $atm$ exerted by $16 \ g$ each of $He$ and $O_2$ in the second container of same volume and temperature is

$1 \ g$ equivalent of a substance is present in:

Write formulas for the following compounds:
$(1)$ Mercury $(II)$ chloride
$(2)$ Nickel $(II)$ sulphate
$(3)$ Tin $(IV)$ oxide
$(4)$ Thallium $(I)$ sulphate