Answers26-27 CFISD TX-Chemistry A CRPeriodic Trends

Periodic Trends — Unit test Answers

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The table below gives the data that is needed to calculate the average atomic mass of element B.IsotopeAtomic mass (amu)Relative abundance (%)B-1010.0119.91B-1111.0180.09Based on these data, what is the average atomic mass of element B?

A
10.01
B
10.51
C
10.81
D
11.01
2
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Which will most likely lead to new scientific discoveries in future years?

A
current scientific knowledge
B
current science fiction movies
C
reduction of the elementary school science curriculum
D
rejection of all new scientific ideas
3

Yusef adds all of the values in his data set and then divides by the number of values in the set.What is Yusef most likely finding?

A
the percent error
B
the median
C
the standard deviation
D
the mean
5

Which of these properties is the best one to use for identification of an element?

A
the number of neutrons in the atomic nucleus
B
the number of protons in the atomic nucleus
C
the number of isotopes that are formed by the element
D
the number of charges on ions of the element
6

Which statement describes heterogeneous mixtures?

A
They are made up of two or more pure substances that are not chemically bonded together and appear non-uniform.
B
The substances they are composed of can only be separated chemically.
C
The substances they are composed of have fixed ratios between their components.
D
They are made up of two or more pure substances that are chemically bonded together and appear uniform.
7

In the human body, a series of chemical reactions results in the making of energy that is used at both the cellular and organismal levels. In which course would a person most likely study these chemical reactions?

A
biochemistry
B
geochemistry
C
materials chemistry
D
physical chemistry
8

Which is a correct comparison between the modern quantum model and John Dalton’s model of the atom?

A
The modern model is not as widely accepted by scientists as Dalton’s model.
B
The modern model states that atoms of all elements are identical, whereas Dalton’s model does not.
C
The modern model recognizes particles in the atom, whereas Dalton’s model does not.
D
The modern model does not explain emission spectra, whereas Dalton’s model does.
9

What did J. J. Thomson observe when he applied electric voltage to a cathode ray tube in his famous experiment?

A
The stream of cathode ray particles was moving very slowly.
B
The glass opposite of the negative electrode started to glow.
C
The electric voltage had little effect on the stream of particles.
D
The tube contained two pieces of metal that served as electrodes.
10

The symbol for xenon (Xe) would be a part of the noble gas notation for the element

A
antimony.
B
cesium.
C
radium.
D
uranium.
11

Which of the following observations would indicate that a material is a pure substance?

A
It does not dissolve in water.
B
It changes color after heating.
C
It cannot be physically broken down into different types of atoms.
D
It can be physically broken down into different types of molecules.
12

To explain the photoelectric effect, Albert Einstein linked the photoelectric effect to an idea from which scientist?

A
Heinrich Hertz
B
Isaac Newton
C
Max Planck
D
Thomas Young
13

Which best describes the trends in electronegativity on the periodic table?

A
Electronegativity increases up and to the right.
B
Electronegativity increases down and to the left.
C
Electronegativity decreases up and to the left.
D
Electronegativity decreases down and to the right.
15

Which is a component of John Dalton’s atomic theory?

A
The ratio of atoms in a compound can vary.
B
The atoms of a single element differ.
C
An atom is a small particle that cannot be broken down.
D
Atoms of different elements can be identical.
16

What is the predicted order of first ionization energies from highest to lowest for lithium (Li), sodium (Na), potassium (K), and rubidium (Rb)?

A
Rb > K > Na > Li
B
K > Rb > Na > Li
C
Li > Na > K > Rb
D
Rb > K > Li > Na
17

Who reported four “element” classifications, but included some substances that were combinations of elements rather than true elements in his listing?

A
Henry Moseley
B
Dmitri Mendeleev
C
Antoine Lavoisier
D
Johann Dobereiner
18

Which element has an ion that is smaller than an ion of calcium?

A
potassium
B
strontium
C
cesium
D
magnesium
19

Which scientist’s law about the ratios of masses of elements in a compound did John Dalton’s work on the atomic structure help to explain?

A
Democritus
B
J. J. Thomson
C
Ernest Rutherford
D
Joseph Proust
20

The mass number of a chromium atom is 52 and it has 24 protons. How many neutrons does this atom have?

A
24
B
28
C
76
D
80
21

Which is a set of valid quantum numbers?

A
n = 4, l = 4, m = 4
B
n = 1, l = –2, m = 0
C
n = –1, l = 0, m = 0
D
n = 4, l = 3, m = 3
22

Which statement best describes the light that will cause emission of electrons from a given metal through the photoelectric effect?

A
light with a low enough intensity
B
light with a high enough frequency
C
light with a high enough intensity
D
light with a low enough frequency

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