Answer: The volume of oxygen gas at STP is 446 mL
Step-by-step explanation:
STP conditions are:
Pressure of the gas = 1 atm
Temperature of the gas = 273 K
To calculate the volume when temperature and pressure has changed, we use the equation given by combined gas law. The equation follows:

where,
are the initial pressure, volume and temperature of the gas
are the final pressure, volume and temperature of the gas
We are given:

Putting values in above equation, we get:

Hence, the volume of oxygen gas at STP is 446 mL