Answer: 250. K
Explanation: Use the combined gas equation PV/T = PV/T where the left side refers to initial values and the right side refers to final values. In this case, the temperature remains the same, and this can be proved by using the equation: (303.9 kPa)(10.0 L)/(250.0 K) = (30.0 L)(101.3 kPa)/(T). The variable T represents the unknown final temperature. Solving this equation gives us 250. K (3 significant figures from the 30.0 L).