At $T(K)$,a gaseous mixture contains $H_2$ and $O_2$. The total pressure of the mixture is $2 \ bar$. The partial pressure of $H_2$ is $1.778 \ bar$. What is the weight $(w/w)$ percentage of $H_2$ in the mixture?

Which of the following has the least mass?

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:

When $100 \, mL$ of $1 \, M$ $NaOH$ and $10 \, mL$ of $10 \, N$ $H_2SO_4$ solutions are mixed,what will be the nature of the resulting solution?

What volume of $NH_3$ gas at $STP$ would be needed to prepare $100 \ mL$ of $2.5$ molal $(2.5 \ m)$ ammonium hydroxide solution? (Assume the density of the solution is $1 \ g/mL$)

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)