Concept Check Quiz
Chapter 2
1. The idea that matter is “a-tomic” or “not divisible”, which Democritus called an atom is
today classified as (a) a scientific fact; (b) an experimental observation; (c) a hypothesis;
(d) a scientific theory; (e) scientifically false; (f) gibberish.
2. A sulfur atom has twice the weight of an oxygen atom. When sulfur and oxygen
combine to form sulfur dioxide, one sulfur atom is required for every two oxygen atoms.
In the formation of sulfur dioxide, the weight ratio of sulfur to oxygen is (a) 4 to 1; (b) 2
to 1; (c) 1 to 2; (e) 1 to 4.
3. In the formation of sulfur trioxide, the weight ratio of sulfur to oxygen is (a) 6 to 1; (b) 3
to 1; (c) 3 to 2; (d) 2 to 3; (e) 1 to 3; (f) 1 to 6.
4. Which of the following elements are chemically similar to chlorine? (a) Iodine; (b)
Sulfur; (c) Xenon; (d) Bromine; (e) Krypton; (f) Fluorine.
5. What elements, and how many atoms of each does the simple sugar C6H12O6 (“glucose”)
contain? (a) 6 chlorine, 12 helium, 6 ozone (b) 6 carbon, 12 hydrogen, 6 oxygen; (c) 1
chlorine, 1 hydrogen, 1 oxygen; (d) 1 carbon, 1 hydrogen, 1 oxygen; (e) 1 carbon, 2
hydrogen, 1 oxygen.
6. The chemical formula for carbon dioxide is (a) CaO; (b) Ca2O; (c) CO; (d) CD; (e) C2O;
(f) CO2
7. Which of the following observations confirm that we are surrounded by air? (a) Trees
bending in the wind; (b) The fact that we can observe light; (c) Air that you can feel
entering your nose as you breathe; (d) A breeze brushing against your cheek; (e) An airfilled balloon; (f) The fact that a rock falls when you drop it.
8. The universe is only seconds old, a million trillion seconds old, in fact. In powers of 10,
this is (a) 10^14 s; (b) 10^15 s; (c) 10^16 s; (d) 10^17 s; (e) 10^18 s.
9. The diameter of an atomic nucleus is about a hundredth of a trillionth of a meter. In
powers of 10, this is (a) 10^-10 m; (b) 10^-12; (c) 10^-14 m; (d) 10^-15 m; (e) 10^-16 m; (f)
10^-18 m.
10. How many centimeters are there in 6 kilometers? (a) 6,000,000 cm; (b) 600,000 cm; (c)
60,000 cm.
11. The quantum theory of the atom agrees with every experiment to date. (a) Thus it can
now be called an accepted fact rather than merely a theory; (b) Thus it can now be called
a scientific hypothesis; (c) Thus it is now known to be certainly true, although we still
refer to it as a “theory”; (d) Nevertheless, it remains only a theory and thus is basically
just a guess; (e) Thus it is properly called a scientific theory although, like all theories, it
is somewhat tentative; (f) Nevertheless, it could still be disproved by future experiments.
12. Some people have suggested that another substance, other than carbon, might
conceivably be the key element in forming living organisms elsewhere in the universe.
Which of these is the most plausible choice for this substance? (a) silicon; (b) oxygen; (c)
chlorine; (d) argon; (e) neon; (f) peanut butter.
Answers
Chapter 2
1. d (in Democritus’s time this was a hypothesis, but today it is an established scientific
theory). It is incorrect to call a general idea, such as this one, a fact or observation.
2. c (the weight of one sulfur atom is the same as the weight of two oxygen atoms, so the
ratio is 1 to 1).
3. d (now the ratio is 1 to 1.5, which is the same as 2 to 3)
4. a, d, & f
5. b
6. f
7. a, c, d, and e (we can also observe the light from stars (answer “b”), despite the absence
of air in outer space and a rock would still fall (answer “f”) even if there were no air.
8. e
9. c
10. b
11. e & f (d is wrong: a hypothesis is an educated guess, but a theory is far more than that)
12. a