One mole of methanol when burnt in excess of $O_2$ releases $723 \ kJ \ mol^{-1}$ of heat. If $1 \ mol$ of $O_2$ is used,what will be the amount of heat evolved in $kJ$?

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 $CO_2$?

What volume in $mL$ of $73 \ g/L$ hydrochloric acid is required to completely neutralize the sodium hydroxide produced by the reaction of $0.46 \ g$ of sodium metal with water?

$100 \ mL$ of $PH_3$ when completely decomposed produces phosphorus and hydrogen. The change in volume of the gas is
$PH_{3(g)} \longrightarrow P_{(s)} + \frac{3}{2} H_{2(g)}$

$23 \ g$ of $Na$ will react with methyl alcohol to give:

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A:$ $3.1500 \ g$ of hydrated oxalic acid dissolved in water to make $250.0 \ mL$ solution will result in $0.1 \ M$ oxalic acid solution.
Reason $R:$ Molar mass of hydrated oxalic acid is $126 \ g \ mol^{-1}$.
In the light of the above statements,choose the correct answer from the options given below: