Final answer:
Based on Boyle's Law, the new pressure should be calculated as 1.80 atm. However, since that option is not given, there might be an error in the provided answers or the question itself, making the exact answer indeterminable with the options provided.
Step-by-step explanation:
The calculation of the internal pressure of a helium balloon when compressed is a classic application of Boyle's Law, which states that for a given mass of an ideal gas, pressure is inversely proportional to volume when the temperature is constant. Therefore, if a 2 L helium balloon at atmospheric pressure (1 atm) is compressed to 1.11 L, we use Boyle's Law: P1 x V1 = P2 x V2, where P1 is the initial pressure, V1 is the initial volume, P2 is the final pressure, and V2 is the final volume.
Given P1 = 1 atm, V1 = 2 L, and V2 = 1.11 L, we solve for P2: P2 = (P1 x V1) / V2 = (1 atm x 2 L) / 1.11 L = 1.80 atm (approximately).
However, since the options provided do not include 1.80 atm, the closest answer would be C) 1.5 atm, which might suggest that there was a miscalculation or an error in the options provided. Therefore, with the information given, we cannot determine the exact answer and instead suggest rechecking the calculations or possible options for a precise result.