How many atoms of he gas are present in a 450 ml container at 35°c and 740 mmhg?

To answer this question, we will need to use the gas law which states that:
PV = nRT where:
P is the pressure of the gas = 740 mmHg = 98658.550357 Pascal
V is the volume = 450 ml = 0.45 liters
n is the number of moles that we will calculate
R is the gas constant =  8.314 J/(K. mol)
T is the temperature = 35 celcius = 308 degrees kelvin

Substitute with these values in the above equation to get the number of moles as follows:
98658.550357 * 0.45 = n * 8.314 * 308
n = 17.3375 moles

Each mole contains Avogadro's number of atoms, therefore:
number of atoms = 17.3375 * 6.02 * 10^23 = 1.0437 * 10^25 atoms