Q: What is the state of matter that resembles a gas, but is made of ions, giving it different properties than a typical gas? Choices: - gamma - vapor - acid - plasma A:
plasma

Q: What is the process by which a liquid changes to a solid? Choices: - melting - vaporizing - boiling - freezing A:
freezing

Q: What are the two main types of air pollutants? Choices: - a and b - new and old - good and bad - primary and secondary A:
primary and secondary