5. Which one is the correct statement?
a. Compounds that taste sour are called bases. b. Sodium hydroxide, calcium hydroxide are examples of acids.
C. Compounds that usually taste bitter are called acids.
d. Compounds may be grouped into acids, bases, or salts.

6. Which of the following is correctly matched?
a. Saltwater: Homogeneous; coffee: Heterogeneous
b. Air: Homogeneous; concrete: Heterogeneous
C. Vinegar: Homogeneous; blood: Heterogeneous
d. Ice cubes in a soda: Homogeneous; coffee: Heterogeneous

7. What is the difference between a substance and a mixture?
a. Substance can be separated while mixture cannot be separated.
b. Substance has many components while mixture has one only.
C. Substance is heterogeneous while mixture is homogeneous.
d. Substance is pure while mixture is impure.​