The weight of calcium oxide formed by burning $20 \ g$ of calcium in excess oxygen is $.... \ g$

In the bromination of propyne,$1,1,2,2-$tetrabromopropane is obtained in $27\%$ yield. The amount of $1,1,2,2-$tetrabromopropane obtained from $1 \; g$ of bromine $(Br_2)$ in this reaction is $\dots \; \times 10^{-1} \; g$. (Nearest integer)
(Molar mass: Bromine $(Br)$ $= 80 \; g/mol$)

Calculate the percent atom economy when a product of formula weight $175 \ u$ is obtained in a chemical reaction using $225 \ u$ formula weight reactant. (in $\%$)

$X$ litres of carbon monoxide is present at $STP$. It is completely oxidized to $CO_2$. The volume of $CO_2$ formed is $11.207$ litres. What is the value of $X$ in litres?

Find the mass of potassium chlorate required to liberate $5.6 \ dm^3$ of oxygen gas at $STP$. (Molar mass of $KClO_3 = 122.5 \ g/mol$) (in $g$)

$0.5 \ M$ of $H_2SO_4$ is diluted from $1 \ L$ to $10 \ L$,the normality of the resulting solution is ......... $N$.