Given which are missing in your question: the flask is filled with 1.45 g of argon at 25 C° So according to this formula (Partial pressure): PV= nRT first, we need n, and we can get by substitution by: n = 1.45/mass weight of argon = 1.45 / 39.948 = 0.0363 mol of Ar we have R constant = 0.0821 and T in kelvin = 25 + 273 = 298 and V = 1 L ∴ P * 1 = 0.0363* 0.0821 * 298 = 0.888 atm
