Calculate the amount of $NO_2$ required for producing $4$ moles of $HNO_3$ as per the chemical reaction,$3 NO_2 + H_2O \longrightarrow 2 HNO_3 + NO$. (in $g$)

What is produced when $1 \ mol$ of calcium phosphide reacts with excess water?
$(Hint: Ca_3P_2 + H_2O (excess) \rightarrow Ca(OH)_2 + 2PH_3)$

$A$ sample of $NaClO_3$ is converted by heat to $NaCl$ with a loss of $0.16 \ g$ of oxygen. The residue is dissolved in water and precipitated as $AgCl$. The mass of $AgCl$ (in $g$) obtained will be (Given: Molar mass of $AgCl = 143.5 \ g \ mol^{-1}$)

The volume (in $mL$) of $0.1\, N$ $NaOH$ required to neutralize $10\, mL$ of $0.1\, N$ phosphinic acid is........

How many $g$ of a dibasic acid (Mol. wt. $= 200$) should be present in $100 \ mL$ of its aqueous solution to give decinormal strength?

Calculate the molarity $(M)$ of a $H_2SO_4$ solution that has a density of $1.84 \ g/mL$ and is $98 \% \, w/w$.