the temperature of n = 19 mol of argon gas is increased from T1 = 21 oC by Q = 4.4 kJ heat transfer, while the gas pressure is kept constant. What is the new gas temperature in Celsius degrees?

Q=n*Cv*(change in temp) as its a monoatomic gas I think this means that the equation is just Q=Cp*change in temp. But I'm not really sure. The Cv of Argon is 0.3122, with R being 0.2081 and Cp being 0.5203.

My last attempts have come up with the final temp as 44.9 - where I had used the mass of the object as 749. I also have got 30.88 and 29.40 by subbing the values into the unknown. I keep getting the answer marked as wrong and I'm not sure where I'm going wrong. Are any of these values correct