1. Which of the following is an element?
(A) Iron
(B) Air
(C) Water
(D) Salt
2. What is a compound?
(A) A substance made of only one kind of atom
(B) A mixture of elements and compounds
(C) A substance formed by the chemical combination of two or more elements
(D) A substance that can be physically separated
3. Which of the following is a mixture?
(A) Sodium chloride
(B) Distilled water
(C) Carbon dioxide
(D) Seawater
4. Which of the following can be separated by physical means?
(A) Compound
(B) Mixture
(C) Element
(D) Atom
5. Which of these is a compound?
(A) Oxygen
(B) Carbon
(C) Hydrogen
(D) Carbon dioxide
6. Air is best described as a:
(A) Compound
(B) Mixture
(C) Molecule
(D) Pure substance
7. Which of the following is not a characteristic of a compound?
(A) Can be separated by physical methods
(B) Has a fixed composition
(C) Formed by chemical reactions
(D) Has different properties from its elements
8. What is the smallest unit of an element?
(A) Compound
(B) Molecule
(C) Atom
(D) Ion
9. Salt dissolved in water is an example of:
(A) A compound
(B) An element
(C) A heterogeneous mixture
(D) A homogeneous mixture
10. Which of the following is a heterogeneous mixture?
(A) Sugar solution
(B) Salad
(C) Air
(D) Vinegar