How many moles of $NaOH$ are present in $27 \, mL$ of $0.15 \, M \, NaOH$?

The molarity of a $98\%$ by weight solution of $H_2SO_4$ is .......... $M$. The density of the solution at $35^o C$ is $1.84 \ g/cm^3$.

Assuming complete decomposition,the volume of $CO_2$ released at $STP$ on heating $9.85 \ g$ of $BaCO_3$ (Atomic mass of $Ba = 137$) will be ................ $L$.

If $0.5 \ g$ of a mixture of two metals $A$ and $B$ with respective equivalent weights $12$ and $9$ displace $560 \ mL$ of $H_2$ at $STP$ from an acid,the composition of the mixture is:

$LiOH$ reacts with $CO_2$ to form $Li_2CO_3$ (atomic mass of $Li = 7$). The amount of $CO_2$ (in $g$) consumed by $1\, g$ of $LiOH$ is closest to $....\, g$

Galena (an ore) is partially oxidized by passing air through it at high temperature. After some time,the passage of air is stopped,but the heating is continued in a closed furnace such that the contents undergo self-reduction. The weight (in $kg$) of $Pb$ produced per $kg$ of $O_2$ consumed is $. . . . .$ (Atomic weights in $g \ mol^{-1}: O = 16, S = 32, Pb = 207$)