AnswersLA-Chemistry AUnit Test

Unit Test — Unit test Answers

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Which element is classified as an alkali metal?

A
Rb
B
Sr
C
Zr
D
Cl
2
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When electrons are removed from the outermost shell of a calcium atom, the atom becomes

A
an anion that has a larger radius than the atom.
B
an anion that has a smaller radius than the atom.
C
a cation that has a larger radius than the atom.
D
a cation that has a smaller radius than the atom.
3

Which statement best describes how electrons fill orbitals in the periodic table?

A
Electrons fill orbitals in order of their increasing energy from left to right.
B
Electrons fill orbitals in order of their increasing energy from right to left.
C
Elements fill orbitals in order of increasing energy from top to bottom in each group.
D
Elements fill orbitals in order of increasing energy from bottom to top in each group.
4

Which element has the largest atomic radius?

A
As
B
N
C
P
D
Sb
5

How did Niels Bohr describe electrons in his atomic model?

A
Their energies can have any values.
B
Their exact positions cannot be known.
C
They have high probability to be found in certain regions.
D
They orbit the central nucleus in discrete paths.
6

What did Ernest Rutherford’s gold foil experiment demonstrate about an atom?

A
Each atom is composed of electrons and positive material.
B
The mass of the atom is evenly spread throughout the atom.
C
Neutrons are located in the center of the atom.
D
Positive charge occupies a very small volume in the atom.
7

How many valence electrons does aluminum (Al) have available for bonding?

A
1
B
2
C
3
D
4
8

The diagram below shows some subatomic particles.Which of these statements best identifies the particle that is labeled with an X?

Question illustration
A
It is either a nucleus or a proton.
B
It is either a proton or a neutron.
C
It is either a neutron or an electron.
D
It is either an electron or a nucleus.
9

Which characteristic is given by the angular momentum quantum number?

A
orbital size
B
orbital mass
C
orbital shape
D
orbital orientation
10

To show the electron configuration for an atom, when would it be better to use an orbital notation than to use a written configuration with numbers, letters, and superscripts?

A
when the aim is to use less space
B
when the aim is to show electron spins
C
when the aim is to show orbital shapes in subshells
D
when the aim is to show electron distributions in shells
11

The elements of which group are nonreactive?

A
halogens
B
alkaline earth metals
C
noble gases
D
alkali metals
12

Which physical method can be used for obtaining a sample of salt from a small beaker of salt water?

A
boiling
B
freezing
C
chromatography
D
sorting
13

Air is made up of different gases, such as oxygen, nitrogen, and carbon dioxide. Which statement best describes these three components of air?

A
Oxygen, nitrogen, and carbon dioxide are all classified as pure substances.
B
Oxygen, nitrogen, and carbon dioxide cannot react with another substance.
C
Oxygen, nitrogen, and carbon dioxide are chemically bonded to one another.
D
Oxygen, nitrogen, and carbon dioxide can be classified as elements.
14

Which scientist is known for developing the planetary model of the atom?

A
Niels Bohr
B
Albert Einstein
C
Johannes Rydberg
D
Robert Millikan
15

A single atom of an element has 11 protons, 11 electrons, and 12 neutrons. Which element is it?

A
V
B
Na
C
Mg
D
Se
16

Who was the first to propose the existence of atoms?

A
John Dalton
B
Democritus
C
Joseph Proust
D
Ernest Rutherford
17

Hydrogen has three isotopes 1H, 2H, and 3H. What is the difference between these three isotopes?

A
The number of protons ranges from 1 to 3.
B
The number of electrons ranges from 1 to 3.
C
The number of neutrons ranges from 0 to 2.
D
The number of protons ranges from 0 to 2.
18

Among the elements of the main group, the general trend in the first ionization energy moving across a period is not followed between group 2 and group 13. Which best explains these exceptions?

A
The ionization energy decreases because the full s orbital shields the electron entering the p orbital.
B
The ionization energy increases because the full s orbital shields the electron entering the p orbital.
C
The ionization energy decreases because the stability of the half-full p subshell is increased.
D
The ionization energy increases because the stability of the half-full p subshell is increased.
19

Which pure substance can be classified as an element?

A
H2
B
NO3
C
NaCl
D
H2SO4
20

Which element has 32 protons in its nucleus?

A
phosphorus
B
cobalt
C
germanium
D
sulfur

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