Q: Is an object floating on top of the water considered an additive to the water? A National FAQ said that the water must be without additives. (Section: 4 / Part: b / Paragraph: iv / Line: 1)
A: Additives change chemical or physical properties of the water (e.g. adding salt to change its conductivity, or adding soap to change its surface tension). Water that enters the container must be without such additives. Once the water enters the container, it may mix with/come into contact with anything, including floating objects.
Q: If a balloon is inflated downwards, is it considered "guided" by gravity? (Section: 4 / Part: b / Paragraph: i / Line: 1)
A: No, it isn't. The natural weight of the balloon is not considered a guide.