What is the value of percent atom economy when an organic compound of formula weight $75 \ u$ is obtained from reactants having sum formula weight $225 \ u$?

At $NTP$,$40 \, mL$ of nitrogen reacts with hydrogen to form ammonia. According to the reaction $N_2 + 3H_2 \rightarrow 2NH_3$,the mass of ammonia formed will be ..... (in $, g$)

Heating oxygen in the presence of a catalyst results in $15\%$ conversion to ozone. How many grams of oxygen are required to produce $33.6 \ L$ of $O_3$ at $STP$?

The amount of $50\% \ (w/w)$ solution of hydrochloric acid required to react with $200 \ g$ of $CaCO_3$ would be (in $g$)

In the balanced combustion reaction of $1 \, mol$ of $C_xH_{2n-2}$ hydrocarbon,the coefficients of $O_2$,$CO_2$,and $H_2O$ will be respectively ...

$100 \, mL$ of $0.1 \, N \, HCl$ is neutralized by $0.2 \, N \, NaOH$ solution. After adding $30 \, mL$ of $NaOH$ solution,the neutralization is continued using $0.25 \, N \, KOH$. Calculate the volume of $KOH$ in $mL$ required to complete the neutralization.