A 1.50 liter flask at a temperature of 25°C contains a mixture of 0.158 moles of methane, 0.09 moles of ethane, and 0.044 moles of butane. What is the total pressure of the mixture inside the flask?

The total amount of moles inside the flask is

n = 0.158 + 0.09 + 0.044 = 0.292 mole

According to Boyle's Law, the total pressure of a mixture in a container does not depend on the identity of the gas and only on the amount of the number of moles. So, assuming the mixture behaves like an ideas gas:

P = nRT/V = 0.292 (0.08206) (25+273) / (1.50)

P = 4.76 atm