Question 11 (2 points) A student thinks that scientific theories are not reliable sources of information, since scientists tend to argue about the details of them. What is the flaw in the student's reasoning? (2 points)

a
The arguments between scientists tend to make theories stronger, not weaker.

b
Scientists rarely disagree about scientific theories.

c
Scientific theories do not change over time, which makes them reliable.

d
It is rare for a scientific theory to be valid for more than a few years.

Question 12 (2 points)
Which describes the current model of the atom? (2 points)

a
It can be used to predict atomic behavior in most circumstances.

b
It has been perfected and will never be changed in the future.

c
It is only accepted by a small fraction of scientists.

d
It is only useful in very specific circumstances.

Question 13 (2 points)
Which subatomic particles have an electrical charge? (2 points)

a
Electron and proton

b
Neutron and proton

c
Only electron

d
Only proton

Question 14 (2 points)
A student thinks that the more protons an atom has, the more reactive it will be. Which will best disprove this student's idea? (2 points)

a
Compare the reactivities of lithium (Li) and krypton (Kr).

b
Note that rubidium has 48 neutrons.

c
Compare the number of protons in cesium (Ce) and xenon (Xe).

d
Count the number of neutrons in an atom of helium.

Question 15 (2 points)
Which element has a larger atomic number than silver (Ag)? (2 points)

a
Pd

b
Cu

c
Ni

d
Hg

Question 16 (2 points)
How do scientists use creativity in their careers? (2 points)

a
Devising a hypotheses involves creating new explanations for phenomena.

b
The most important part of an experiment is how colorfully the data is displayed.

c
Scientific results must be explained in a creative, exciting way.

d
Scientists judge each others' work based mostly on how creative it is.

Question 17 (2 points)
What does the position of magnesium (Mg) on the periodic table tell you about how it reacts with other elements? (2 points)

a
It is in the second column, so it tends to gain two electrons.

b
It is in the second column, so it tends to lose two electrons.

c
It is in the third row, so it tends to lose three electrons.

d
It is in the third row, so it tends to gain three electrons.

Question 18 (2 points)
Which best describes how magnesium (Mg) and oxygen (O) bond? (2 points)

a
They form an ionic bond by exchanging two electrons.

b
They form an ionic bond by exchanging three electrons.

c
They form a covalent bond by sharing one electron.

d
They form a covalent bond by sharing four electrons.

Question 19 (2 points)
Which question could be answered using DNA as a molecular clock? (2 points)

a
How old is a dinosaur bone?

b
How long ago was a dinosaur track left in the mud?

c
How long ago did two species of birds share an ancestor?

d
How old was a bird when it died?

Question 20 (2 points)
Calcium chlorate has the formula Ca(ClO3)2. Which best describes the structure of calcium chlorate? (2 points)

a
One molecule of calcium chlorate contains nine atoms.

b
Calcium chlorate is an element that contains three atoms.

c
It takes nine different elements to make one molecule of calcium chlorate.

d
Calcium chlorate contains two Ca groups.