What weight of sodium hydroxide is required to neutralise $100 \ mL$ of $0.1 \ N - HCl$ (in $g$)?

When a hydrated salt,$Na_2SO_4 \cdot nH_2O$,is heated,it loses $56\%$ of its weight and becomes anhydrous. What is the approximate value of $n$?

An aqueous solution of $4.5 \ g$ oxalic acid $(H_2C_2O_4)$ is made up to $250 \ mL$. Calculate the volume of $0.1 \ N$ $NaOH$ required to neutralize completely $20 \ mL$ of this solution.

Calculate the amount of water $(g)$ produced by the combustion of $16 \ g$ of methane. (in $g$)

How many moles of ammonia are produced by $5$ moles of hydrogen (in $.3$)?

$Elodea$ is an aquatic plant that performs photosynthesis in water. The photosynthesis reaction is given by: $6CO_{2(g)} + 6H_2O_{(l)} \to C_6H_{12}O_{6(aq)} + 6O_{2(g)}$. Calculate the mass of $CO_2$ in $g$ required to produce $112 \, mL$ of oxygen at $STP$.