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 $\%$)

The concentration of a $100 \ mL$ solution containing $X \ g$ of $Na_2CO_3$ (molecular weight $= 106$) is $Y \ M$. The values of $X$ and $Y$ are respectively.

If $1 \, mole$ of $H_3PO_x$ is completely neutralized by $80 \, g$ of $NaOH$,select the correct statement :-

What is the volume (in litres) of oxygen required at $STP$ to completely convert $1.5 \ mol$ of sulphur into sulphur dioxide?

$A$ mixture of $H_2$ and $O_2$ at $1 \, atm$ pressure contains $20 \%$ by weight of $H_2$. Find out the partial pressure of $H_2$ in $atm$.

The yield of each step as actually carried out in the laboratory is given in the reaction scheme below. Calculate the overall percentage yield of the reaction.
$Me_3C-CO-CH_3$ $\xrightarrow{58\% (A)} Me_3C-CO-CH_2Br$ $\xrightarrow{54\% (B)} Me_3C-CH(OH)-CH_2Br$ $\xrightarrow{68\% (C)} Me_3C-CH(O)CH_2$