Answer : The moles of oxygen gas lost are 2.88 mole
Explanation :
According to the Avogadro's Law, the volume is directly proportional to the number of moles of the gas at constant pressure and temperature.
(At constant temperature and pressure)
or,
where,
= initial volume of oxygen gas = 12.6 L
= final volume of oxygen gas = 12.1 L
= initial moles of oxygen gas = 3.0 mole
= final moles of oxygen gas = ?
Now put all the given values in the above formula, we get the final moles of oxygen gas.
Therefore, the moles of oxygen gas lost are 2.88 mole