What quantity of oxygen is required for complete burning of $15.6 \ g$ benzene (in $g$)?

The concentrated sulphuric acid that is peddled commercially is $95\%\, H_2SO_4$ by weight. If the density of this commercial acid is $1.834\, g\, cm^{-3},$ the molarity of this solution is ........... $M$.

$250 \ mL$ of a sodium carbonate solution contains $2.65 \ g$ of $Na_2CO_3$. If $10 \ mL$ of this solution is diluted to $1 \ L$,what is the concentration of the resultant solution (in $M$)?

How many grams of a dibasic acid (molar mass = $200 \ g/mol$) are present in $100 \ mL$ of its $0.1 \ N$ aqueous solution (in $g$)?

While combusting in air, $4 \ g$ of $H_2$ gas was completely converted into water. If $36 \ \mu mole$ of $CO_2$ from air is dissolved into that water, what is the concentration of $CO_2$?

The molecular weight of a gas is $45$. Its density at $STP$ is