Which statement regarding oil and ammonia is true?

The statement that ammonia does not mix with oil and floats is accurate due to the unique properties of both substances. Ammonia is a polar molecule, which tends to make it soluble in water but not in oils, which are non-polar. Consequently, when ammonia is introduced to oil, it separates due to their differing polarities, resulting in the ammonia floating on the surface of the oil.

The other statements do not accurately reflect the properties of the substances involved. Carbon dioxide does not mix well with oil either, as it is also a gas at room temperature and primarily interacts with water. Similarly, oil and sulfur dioxide do not mix effectively due to the same reasons—differences in polarity and state of matter. Therefore, the assertion that ammonia does not mix with oil and floats is the only true statement among the choices presented.