Initial temperature of the gas = 100.0°C + 273 = 373 K
Initial pressure of the gas = 3.0 atm
Final temperature of the gas = 300.0°C + 273 = 573 K
According to Pressure Law,
P₁/T₁ = P₂/T₂
where P₁ and T₁ are the initial pressure and temperature respectively, and P₂ and T₂ are the final pressure and temperature respectively.
Plugging in the given data in Pressure Law we have,
3.0 atm/ 373 K = P₂/573 K
P₂ = (3.0 atm x 573 K)/ 373 K
P₂ = 4.6 atm
Thus, the pressure of the gas at the higher temperature is 4.6 atm.