When are the normality $(N)$ and molarity $(M)$ of a solution equal?

What is the volume in $dm^3$ occupied by $3 \ mol$ of ammonia gas at $STP$?

$A$ $1.85 \ g$ sample of an arsenic containing pesticide was chemically converted to $AsO_4^{3-}$ (atomic mass of $As = 74.9$) and titrated with $Pb^{2+}$ to form $Pb_3(AsO_4)_2$. If $20 \ mL$ of $0.1 \ M \ Pb^{2+}$ is required to reach the equivalence point,the mass percentage of arsenic in the pesticide sample is closest to

In $Fe_{0.96}O$,$Fe$ is present in $+2$ and $+3$ oxidation states. What is the mole fraction of $Fe^{2+}$ ions in the compound?

How many grams of $HCl$ are required to prepare $1500 \, mL$ of $0.1 \, N \, HCl$ aqueous solution?

While combusting in air, $4 \ g$ of $H_2$ gas was completely converted into water. If $36 \ \mu mole$ of $CO_2$ from air is dissolved into that water, what is the concentration of $CO_2$?