AnswersCISD-Chemistry A-CRUnit Test

Unit Test — Unit test Answers

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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.
2
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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.
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

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.
5

Which describes Ernest Rutherford’s experiment?

A
Positive particles are fired at gold foil. Most bounce back, but some pass through.
B
Negative particles are fired at gold foil. Most bounce back, but some pass through.
C
Positive particles are fired at gold foil. Most pass through, but some bounce back.
D
Negative particles are fired at gold foil. Most pass through, but some bounce back.
6

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
7

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.
8

Which element has 32 protons in its nucleus?

A
phosphorus
B
cobalt
C
germanium
D
sulfur
9

Who was the first to propose the existence of atoms?

A
John Dalton
B
Democritus
C
Joseph Proust
D
Ernest Rutherford
10

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.
11

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.
12

Which atomic model was proposed as a result of J. J. Thomson’s work?

A
the plum pudding model
B
the indivisible atom model
C
an atom that had a lot of empty space
D
an atom that had a concentrated nucleus
13

How does the electron-cloud model describe electrons?

A
The exact position of an electron can be known.
B
An electron can be found at certain distances from the nucleus.
C
An electron has a high probability of being in certain regions.
D
Each electron follows a specific path around the nucleus.
14

Which statement describes an electron?

A
It has a positive charge and is located in the nucleus.
B
It has a positive charge and is located in orbitals around the nucleus.
C
It has a negative charge and is located in the nucleus.
D
It has a negative charge and is located in orbitals around the nucleus.
15

How did the development of the earliest idea about atoms differ from the later work of scientists?

A
It was based on sound evidence.
B
There were explanations for the idea.
C
It was based on the thoughts of an early philosopher.
D
There were experiments conducted to support the idea.
16

Which statement about the electron-cloud model is true?

A
It is the currently accepted atomic model.
B
It can easily be replaced by existing models.
C
It specifies the location and momentum of an electron.
D
It does not explain the formation of emission lines.
17

The modern-day quantum model of the atom is better than John Dalton’s model because it

A
has set electron orbits.
B
has positive and negative particles in the nucleus.
C
can be represented in one dimension.
D
answers many questions about atoms.
18

Which observation provided Albert Einstein the clue that he needed to explain the photoelectric effect?

A
Light is made up of extremely small particles.
B
Particles that are emitted from a strip of metal are electrons.
C
Shining light on a metal strip produces emissions.
D
Energy of electrons depends on light’s frequency, not intensity.
19

This flow chart shows the amount of energy that is emitted by each type of light. ultraviolet > blue light > yellow light > red light (maximum energy) (minimum energy)In an experiment, shining which type of light on a strip of metal would be least likely to produce the photoelectric effect?

A
ultraviolet light
B
dim blue light
C
bright red light
D
bright yellow light
20

Which statement is most likely true?

A
Ernest Rutherford’s experiment led to the nuclear model of the atom.
B
Ernest Rutherford’s experiment established the plum pudding model of the atom.
C
Robert Millikan’s postulates form the most accepted theory for the atomic structure.
D
Robert Millikan’s results had little impact on determining of the charge of an electron.

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