If $0.4 \ g$ of $NaOH$ is present in $40 \ mL$ of solution,what will be the molarity and normality? (Molecular weight of $NaOH = 40$)

$A$ $250 \, mL$ solution of $Na_2CO_3$ contains $2.65 \, g$ of $Na_2CO_3$. If $10 \, mL$ of this solution is taken and diluted with distilled water up to $0.1 \, L$,what will be the molarity of the resulting solution (in $, M$)?

How much volume of $1 \,N$ aqueous solution of $H_2SO_4$ should be taken, which will contain $0.2$ moles of $H_2SO_4$ (in $\,mL$)?

$10 \, L$ solution of urea contains $240 \, g$ urea. The active mass of urea will be

The density of $2 \ M$ aqueous solution of $NaOH$ is $1.28 \ g \ cm^{-3}.$ The molality of the solution is $... \ m$ [Given that molecular mass of $NaOH = 40 \ g \ mol^{-1}$]

In the reaction $SO_{2(g)} + 1/2 O_{2(g)} \to SO_{3(g)}$,how many liters of air at $STP$ are required for the complete conversion of $6.4 \, g$ of $SO_2$ to $SO_3$ (in $, L$)? (Assume air contains $20 \% \, O_2$ by volume).