How many moles of potassium chlorate need to be heated to produce $5.6 \, L$ of oxygen at $STP$?

$29.2 \% (w/w)$ $HCl$ stock solution has a density of $1.25 \ g \ mL^{-1}$. The molecular weight of $HCl$ is $36.5 \ g \ mol^{-1}$. The volume $(mL)$ of stock solution required to prepare a $200 \ mL$ solution of $0.4 \ M$ $HCl$ is :

Given the ratio of masses of nitrogen and oxygen in a particular gaseous mixture is $4: 1$. Calculate the ratio of the number of their molecules.

Phosphoric acid $(H_3PO_4)$ is a tribasic acid and one of its salts is sodium dihydrogen phosphate $(NaH_2PO_4)$. What volume of $1 \ M$ $NaOH$ solution should be added to $12 \ g$ of sodium dihydrogen phosphate (mol. wt. $120$) to exactly convert it into trisodium phosphate $(Na_3PO_4)$? (Answer in $mL$)

White phosphorus reacts with chlorine and the product hydrolyses in the presence of water. Calculate the mass of $HCl$ obtained by the hydrolysis of the product formed by the reaction of $62 \ g$ of white phosphorus with chlorine in the presence of water.

In the Victor Meyer method,$0.2 \ g$ of a volatile substance displaces $56 \ mL$ of air at $STP$. The molar mass of the substance is: