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 initial pressure, volume and temperature of the gas
 are the final 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