What is the partial pressure of argon, par, in the flask? express your answer to three significant figures and include the appropriate unit?

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