MULTIPLE-CHOICE QUESTIONS: Choose the most appropriate answer.
1. Atoms of elements
a. can exist independently
b. cannot exist independently
c. may or may not exist independently.
d. can exist independently but don't like to! (c)
2. A molecule of water
a. cannot be broken down.
b. can be broken down by hammering it.
c. can be broken down by boiling the water.
d. can be broken down by passing an electric current through water. (d)
3. There are about 117 different
a. elements
b. molecules.
c. Compounds
d. mixtures (a)
4. If you heat a liquid, it will ultimately change into
a. a solid
b. a gas.
c. either a solid or a gas depending on temperature.
d. neither solid nor gas-it will always remain a liquid. (b)
5. When two elements are brought together, they
a. always form a mixture.
b. always form a compound.
c. may form a mixture or a compound depending on the conditions.
d. may form a mixture or a compound depending on what they like. (c)
6. Which of the following is not a mixture?
a. air b. sea water c. pure water d. soil (c)
7. The valency of which of these elements is zero?
a. iron b. helium c. hydrogen d. oxygen (b)
8. Which of these is the formula for calcium hydroxide?
a. CaOH b. Ca₂OH c. Ca(OH)₃ d. Ca(OH)₂ (d)
9. The equation Na + H₂O ----> NaOH + H₂ is
a. correct
b. incorrect since it is not balanced.
c. incorrect since sodium does not react with water.
d. incorrect since hydrogen should be written as H and not H2. (b)
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