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 $kJ$?

$0.5 \ L$ of gaseous hydrocarbon when burnt in excess of $O_2$ gave $3.5 \ L$ of $CO_2$ and $4 \ L$ of water vapours under same conditions. The molecular formula of the hydrocarbon will be:

At sea level,the dry air mass percentage composition is given as nitrogen gas: $70.0$,oxygen gas: $27.0$,and argon gas: $3.0$. If the total pressure is $1.15 \ atm$,calculate the ratio of the following respectively:
$(i)$ partial pressure of nitrogen gas to partial pressure of oxygen gas
$(ii)$ partial pressure of oxygen gas to partial pressure of argon gas
(Given: Molar mass of $N_2$,$O_2$,and $Ar$ are $28, 32$,and $40 \ g \ mol^{-1}$ respectively)

The volume of $0.02 \, M$ aqueous $HBr$ required to neutralize $10.0 \, mL$ of $0.01 \, M$ aqueous $Ba(OH)_2$ is $....... \, mL$ (Assume complete neutralization).

How many moles of potassium chlorate $(KClO_3)$ are required to be heated to produce $11.2 \text{ L}$ of oxygen gas at $STP$?

$A$ $240 \ mL$ mixture of $CO_2$ and $CO$ is passed over red-hot coke. The $CO_2$ is completely reduced to $CO$. When the resulting gas is brought to the same temperature and pressure,the volume becomes $300 \ mL$. What is the volume of $CO$ in the original mixture in $mL$?