$A$ cold drink bottle contains $200 \ mL$ liquid in which $CO_2$ is $0.1 \ M$. Considering $CO_2$ as an ideal gas,the volume of the dissolved $CO_2$ at $S.T.P$ is: (in $L$)

If $1\frac{1}{2}$ moles of oxygen combine with $Al$ to form $Al_2O_3$,the weight of $Al$ used in the reaction is ............. $g$ $(Al=27)$.

$7.8 \ g$ of a compound having molecular formula $C_6H_6$,on reacting with $CH_3COCl / AlCl_3$ gives $8.4 \ g$ of a product which has molecular formula $C_8H_8O$. Calculate the percentage yield of the product $C_8H_8O$. (Given atomic weights of $H$,$C$ and $O$ respectively are $1$,$12$ and $16$) (in $\%$)

$A$ $100 \ mL$ solution was made by adding $1.43 \ g$ of $Na_2CO_3 \cdot xH_2O$. The normality of the solution is $0.1 \ N$. The value of $x$ is .......... (The atomic mass of $Na$ is $23 \ g/mol$):

$20 \ mL$ of methane is completely burnt using $50 \ mL$ of oxygen. The volume of the gas left after cooling to room temperature is (in $mL$)

$4.0 \,g$ of $NaOH$ are contained in one decilitre of solution. Its molarity would be ......... $M$.