Answer: T = 298.5K
V = 4.60L
m(CO2) = 21.0g
finding moles carbon dioxide : n = m/Mr
= 21g / 44.01 g/mol
= 0.477 mol
then use P = nRT/ V
= 0.477 mol × 0.0821 × 298.5k/ 4.60 L
= 2.54atm
Explanation: pressure can be determined by first finding the number of moles of carbon dioxide.We then deduce the ideal gas formula that provide the the relationship between volume, temperature,pressure and the number of particles in the gas.the equation only makes easier for assumptions which in most cases are not true