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Radioactivity — Unit test Answers

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Consider the three equations below.Which statement do these reactions best support?

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A
Beta decay occurs only in certain atoms.
B
Alpha decay occurs only in certain atoms.
C
Chain reactions play important roles in the process of nuclear fission.
D
Nuclear fusion plays an important role in making elements that are heavier than helium.
2
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Particle A has very little mass in comparison to Particle B. Both particles are in the same atom. Which is the best conclusion about Particles A and B?

A
They have the same charge.
B
They are located in the nucleus together.
C
Particle A has a positive charge, and Particle B is neutral.
D
Particle A orbits the nucleus, and Particle B is located in the nucleus.
3

Students are completing a table about a particular subatomic particle that helps make up an atom.What best explains how they should complete the table?

Question illustration
A
with “Inside the nucleus,” because the particle is a proton
B
with “Inside the nucleus,” because the particle is a neutron
C
with “Outside the nucleus,” because the particle is a proton
D
with “Outside the nucleus,” because the particle is an electron
4

Three radioisotopes are being discussed in a chemistry class. Technetium-99m has a half-life of 6 hours. Rubidium-87 has a half-life of 50 billion years. Which describes who would most likely use each isotope?

A
A geologist would use technetium-99m because short-life indicates an older organism, and a doctor would use rubidium-87 because it allows for a more-accurate measurement of disease.
B
A doctor would use technetium-99m because a short half-life indicates a quick measurement, and a geologist would use rubidium-87 because a longer half-life means that there is a longer time to measure old rock.
C
A doctor would use technetium-99m because a short half-life indicates a quick measurement, and an archeologist would use rubidium-87 because anything containing carbon also contains rubidium.
D
A geologist would use technetium-99m because a short half-life indicates an older organism, and an archeologist would use rubidium-87 because anything containing carbon also contains rubidium.
5

Which have different numbers of electrons?

A
different ions of an element
B
different isotopes of an element
C
the nucleus of an element
D
each of the atoms of an element
6

This is how manganese appears in the periodic table.

Question illustration
A
period symbol of manganese
B
isotope symbol of manganese
C
group symbol of manganese
D
chemical symbol of manganese
7

While looking at bromine (Br) on the periodic table, a student needs to find another element with very similar chemical properties but with a different atomic mass. Which best describes the student’s options?

A
There are two possible elements, and they are directly to the left and right of bromine.
B
There are two possible elements, and they are directly above and below bromine.
C
There are many possible elements, and they are all in the same vertical column as bromine.
D
There are many possible elements, and they are all in the same horizontal row as bromine.
8

How does Rutherford’s model of the atom compare with Thomson’s model?

A
They both describe atoms as small, indivisible spheres.
B
They both describe electrons as moving around the nucleus.
C
They both describe electrons as being surrounded by the positive matter.
D
They both describe atoms as being made up of positive and negative matter.
9

What is an atomic nucleus?

A
the outer part of an atom in which electrons move
B
the outer part of an atom in which neutrons move
C
the central part of an atom, composed of protons and neutrons
D
the central part of an atom, composed of protons and electrons
10

Which best describes nuclear fusion?

A
A nucleus spontaneously splits and absorbs energy.
B
Two nuclei spontaneously combine and absorb energy.
C
A nucleus collides with a neutron and splits, releasing energy.
D
Nuclei combine to form a heavier nucleus, releasing energy.
11

Which best describes what forms in nuclear fission?

A
two smaller, more stable nuclei
B
two larger, less stable nuclei
C
one smaller, less stable nucleus
D
one larger, more stable nucleus
12

An atomic physicist determines that an atom is composed of 8 positively charged particles and has a mass of 15 amu. Which is the best conclusion that can be drawn?

A
The atom has 7 neutrons and 8 protons.
B
The atom has 7 electrons and 8 protons.
C
The atom has 8 neutrons and 7 electrons.
D
The atom has 8 electrons and 7 protons.
13

Which describes radioactive decay of a substance?

A
More of the radioactivity is lost during the first half-life than in later half-lives.
B
More of the radioactivity is lost during the fourth half-life than in the first half-life.
C
Isotopes are the most stable during the first half-life.
D
Isotopes are the least stable during the later half-lives.
14

A sample is in the second half-life. What percent of the sample is stable at this point?

A
12.5%
B
25%
C
50%
D
75%
15

Atoms of two different elements must have different

A
electrical charges.
B
numbers of neutrons.
C
atomic numbers.
D
energy levels.

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