What amount of oxygen is used at S.T.P. to obtain 9 g water from sufficient amount of hydrogen gas?

What is value of percent atom economy if formula weight of product is 46 u and sum of formula weight of all reactants is 92 u?

$$60 \mathrm{~g} \mathrm{~CH}_3 \mathrm{COOH}$$ dissolved in $$1 \mathrm{~dm}^3$$ solvent, what is molality of solution?

(density = $$1.25 \mathrm{~g} / \mathrm{cm}^3$$)

What is the molarity of solution containing $$3.2 \mathrm{~g}$$ of $$\mathrm{NaOH}$$ (molar mass $$40 \mathrm{~g} \mathrm{~mol}^{-1}$$) in $$250 \mathrm{~cm}^3$$ of water?