Question 1: Which of the following is a compound?

Answer: Water

Question 2: True or False: An element is a substance made of only one type of atom.

Answer: True

Question 3: What is the smallest unit of a chemical element that retains its chemical properties?

Answer: Atom

Question 4: How many atoms are there in a molecule of water (H₂O)?

Answer: 3

Question 5: Match the following terms to their definitions:

Answer: See full answer key

Question 6: What is the atomic number of an element and why is it important?

Answer: The atomic number is the number of protons in an atom's nucleus, determining the element.

Question 7: Calculate the number of moles in 18 grams of water. (Molar mass of H₂O = 18 g/mol)

Answer: 1 mole

Question 8: True or False: Compounds can be separated into their elements by physical means.

Answer: False

Question 9: Fill in the blank: A _______ is a substance made from two or more elements that are chemically bonded.

Answer: compound

Question 10: Order the following steps in the process of forming a compound: (1) Atoms bond together, (2) Elements react, (3) New substance forms.

Answer: See full answer key

Question 11: Explain the difference between an atom and a molecule and give an example of each.

Answer: An atom is the smallest unit of an element, such as a hydrogen atom. A molecule is a group of atoms bonded together, such as a water molecule (H₂O).

Question 12: Describe how compounds are different from mixtures, providing examples for each.

Answer: Compounds are substances formed from two or more elements chemically bonded, such as NaCl (salt). Mixtures are combinations of substances not chemically bonded, like salt and sand.