Answer:
[tex]T = 154.028\,K[/tex]
Explanation:
Let consider that helium behaves ideally. The equation of state of the ideal gas is:
[tex]P \cdot V = n \cdot R_{u}\cdot T[/tex]
The temperature is cleared in the expression presented above:
[tex]T = \frac{P\cdot V}{R_{u}\cdot n}[/tex]
The temperature of the helium inside the balloon is:
[tex]T = \frac{(1.26\,atm)\cdot (1.25\,L)}{\left(0.082\,\frac{atm\cdot L}{mol\cdot K} \right)\cdot (0.1247\,mol)}[/tex]
[tex]T = 154.028\,K[/tex]
