Answer:
Firstly, calculate the Pressure of the gas using the Ideal Gas Law:
PV = nRT
where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature.
Next, convert the units of temperature and pressure from Celsius and millimeters of mercury (mmHg) to Kelvin and atmospheres (atm), respectively.
At 20°C, the temperature in Kelvin is 293K and the pressure in atm is 0.976atm.
Now, calculate the volume of the gas at STP (standard temperature and pressure). At STP, the temperature is 273K and the pressure is 1atm.
Using the Ideal Gas Law, we can solve for the new volume:
V2 = nRT2/P2
V2 = (nRT1/P1) x (P2/T2)
V2 = 200cm^3 x (1atm/293K) x (273K/0.976atm)
V2 = 224.6cm^3