Answers26-27 CFISD TX-Chemistry A CRPeriodic Trends

Periodic Trends — Unit test Answers

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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.
2
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A teacher discusses a scientific theory that has been in place for almost a century. Which would present the greatest challenge to this theory?

A
lists of what the theory cannot explain
B
discussion of the theory on Internet blogs
C
results from new experiments that contradict the theory
D
opinions of a vocal group of citizens that oppose the theory
3

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

A
Niels Bohr
B
Albert Einstein
C
Johannes Rydberg
D
Robert Millikan
4

Which factor is most important to consider when evaluating a journal article about global warming?

A
Is the article long enough?
B
Does the article contain facts or only opinions?
C
Did the author of the article use complex, scientific words?
D
Does the author of the article have a doctorate degree?
5

Which best explains why openness is important to the progress of science?

A
It aids in the analysis of complicated numerical data.
B
It aids in understanding technical papers in academic journals.
C
It allows scientists to consider ideas that contradict their models or theories.
D
It allows scientists to design novel experiments that may be difficult to carry out.
6

To which scientific discipline are the fields of geology, materials, and nutrition best related?

A
physics
B
biology
C
chemistry
D
pharmaceuticals
7

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
8

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.
9

Which best explains why ionization energy tends to decrease from the top to the bottom of a group?

A
The number of orbitals decreases.
B
The number of neutrons decreases.
C
Electrons get closer to the nucleus.
D
Electrons get farther from the nucleus.
10

How is the mode of a data set defined?

A
It is the middle value of the set.
B
It is the most common value in the set.
C
It is the average of the different values in the set.
D
It is the difference between the highest and lowest values of the set.
11

Boyd takes additional measurements of the mass of product formed in a reaction. He uses a balance that has smaller graduations than the first balance he used. What is Boyd most likely trying to change?

A
He is trying to increase his accuracy but not his precision.
B
He is trying to increase his precision but not his accuracy.
C
He is trying to decrease his precision and increase his accuracy.
D
He is trying to increase his precision and decrease his accuracy.
12

Which element is the most reactive?

A
sodium
B
nickel
C
carbon
D
oxygen
13

Which of Dalton's ideas about the atom did J.J. Thomson's experiment disprove?

A
It disproved that atoms are divisible.
B
It disproved that atoms are indivisible.
C
It disproved that atoms contain protons.
D
It disproved that atoms contain electrons.
14

Which of the following symbols would be included in the noble gas notation for an element that had valence electrons in the 5s subshell?

A
Ar
B
Kr
C
Xe
D
Rn
15

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

A
1
B
2
C
3
D
4
16

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
17

Iron, an element with the chemical symbol Fe, is an important element. It is used to make steel and is part of the substance that transports oxygen throughout the human body.Which statement about Fe is supported by the modern atomic theory but not John Dalton’s theory?

A
The element iron is composed of small particles called atoms.
B
The electrons of iron have probable locations in a region of space around the nucleus.
C
Iron atoms combine with other atoms in whole number ratios to form compounds.
D
Chemical reactions that involve iron do not create new atoms of iron.
18

Which is a correct set of values of m for one of the subshells of n = 2?

A
–1, 0, 1
B
–1, –2, 0, 1, 2
C
–1, –2, –3, 0, 1, 2, 3
D
–1, –2, –3, –4, 0, 1, 2, 3, 4
19

Who was the first to propose the existence of atoms?

A
John Dalton
B
Democritus
C
Joseph Proust
D
Ernest Rutherford
20

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

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