Find the volume of O₂ required to burn 1 L of propane completely, measured at 0℃ temperature and 1 atm pressure

The correct option is 5 L.

To understand why this is the correct answer, we can look at the chemical reaction for the complete combustion of propane ($C_3{H}_8$).

The balanced chemical equation for the complete combustion of propane in the presence of oxygen ($O_2$) is:
$C_3{H}_8\left(g\right)+5O_2\left(g\right)\to 3C{O}_2\left(g\right)+4H_{2}O\left(l\right)$

According to Gay-Lussac's Law of Combining Volumes, when gases react together, they do so in volumes which bear a simple whole-number ratio to one another, provided the temperature and pressure remain constant.

From the balanced chemical equation, we can see the stoichiometric ratio between propane gas ($C_3{H}_8$) and oxygen gas ($O_2$):
1 volume of $C_3{H}_8$ requires 5 volumes of $O_2$ for complete combustion.

Since both gases are measured at the same temperature (0℃) and pressure (1 atm), the volume ratio is directly proportional to their mole ratio:
Volume of $O_2$ = 5 × Volume of $C_3{H}_8$

Given that the volume of propane is 1 L:
Volume of $O_2$ = 5 × 1 L = 5 L

Therefore, 5 L of oxygen gas ($O_2$) is required to burn 1 L of propane completely.