1. A substance with a definite mass but no definite volume or shape is a gas. Gas particles are spread far apart from one another, and they are constantly in motion such that they will fill up any container that they’re in. So the correct answer for 1 would be the first answer choice.
2. A liquid has a definite mass (all of the common states of matter have definite mass) and it has a definite volume: The particles of a given mass of liquid will occupy the same amount of space regardless of the shape of the liquid’s container; it likewise follows that a liquid does not have a definite shape. So, while one liter of water can fill and take the “shape” of a bowl or a bottle, there will always be one liter of water in each. So, the correct answer here would be the fourth answer choice.
3. A solid has a definite mass, a definite shape, and a definite volume precisely because its particles are not free to zip around freely (or rapidly). So the fourth statement is not true, and thus the fourth answer choice would be the correct answer here.
The Pauli Exclusion Principle states that, in an atom or molecule, no two electrons can have the same four electronic quantum numbers. As an orbital can contain a maximum of only two electrons, the two electrons must have opposing spins.
