The objects with a mass of X, 2X, and 3X are all brought to a planet without gravity. Each object is propelled forward with a force of 100N, using Newton's law, what should be true about each objects acceleration

Using F = ma;

Since F is the same for all three cases, the mass times the acceleration for each situation must equal 100. So the object with mass X will have a greater acceleration than object 2X, which will have a greater acceleration than an object with 3X.