We're dealing with a gas here, so let's apply the Ideal Gas Law

pV = nRT

Since we're not interested in the type of gas, i.e. moles,
we'll ignore both n and R and end up with

pV = nRT

Now, we can set up a ratio between
the initial and the final state of this gas

(p_initial)(V_initial) / T_initial

=

(p_final)(V_final) / T_final

Kelvin

Let's convert our temperatures, so the units fit 100 °C + 273.15 = 373.15 K 0 °C + 273.15 = 273.15 K

chemistry kicks anatomy

Let's plug in the info provided (1 atm)(300. L) / 373.15 K = (1.25 atm)(L) / 273.15 K

Celcius

And now we solve for V_final

L =

(1 atm)(300. L_initial) (273.15 K) / (373.15 K)(1.25 atm)

V_final = 175.6827

The final volume of this nitrogen gas is 175.68 L
considering sig figs, it is 2.0 x 10² L