AnswersTX-Chemistry A-CRCumulative Exam

Cumulative Exam — Cumulative exam Answers

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21
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The figure shows the hybrid orbitals of methane. Which molecule has the same shape and hybridization as methane?

Question illustration
A
SO3
B
C2H2
C
CH2O
D
CF2Cl2
22
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A single atom of an element has 21 neutrons, 20 electrons, and 20 protons. Which element is it?

A
K
B
Zr
C
Ca
D
Sc
23

What is the true ratio of atoms in a molecule or formula unit called?

A
the molecular formula
B
the molar mass
C
the percent composition
D
the empirical formula
24

Derek needs a tool that delivers 5.00 mL of a sodium hydroxide solution. Which tool would be best for him to use?

A
a beaker
B
a pipette
C
a graduated cylinder
D
an Erlenmeyer flask
25

Assuming the compound is dissolved in water, what is the formula for phosphorous acid?NameSymbolphosphatePOphosphitePOphosphorusP

Question illustration
A
H3P
B
H3PO4
C
HP
D
H3PO3
26

The MSDS for propane gives it a health rating of 1, a flammability rating of 4, and a reactivity rating of 0. According to the MSDS, which best describes propane?

A
highly corrosive
B
highly toxic
C
highly flammable
D
highly reactive
27

Which diagram shows electrons violating the Pauli exclusion principle?

A
A box contains an up arrow.
Option A
B
A box contains an up and a down arrow.
Option B
C
A box contains an up and a down arrow.
Option C
D
A box contains an up and a down arrow.
Option D
28

A teacher wants to perform a classroom demonstration that illustrates both chemical and physical changes. Which would be the best demonstration that she could use?

A
bending a piece of aluminum
B
breaking a matchstick
C
dissolving sugar in water
D
burning a candle
29

In an investigation that uses the scientific method, which step immediately follows making a hypothesis?

A
summarizing the results
B
asking a question
C
making observations
D
designing an experiment
30

Consider the balanced equation. PCl3 + 3H2O H3PO3 + 3HCl What is the percent yield of HCl if 42.0 g of HCl are produced from the reaction of 62.0 g of PCl3?Use .

Question illustration
A
28.4%
B
72.8%
C
85.0%
D
93.5%
31

Why is it advisable to wear long sleeves when students work in a chemistry lab?

A
to provide warmth near the lab refrigerator
B
to protect the arms from lab chemicals
C
to minimize burns from hot water at the lab sink
D
to prevent burns when using a Bunsen burner
32

What is the best reason for the scientific community to accept a theory?

A
The theory is supported by all the available observations and data.
B
An award-winning scientist proposed the theory.
C
The majority of the general public agrees with the theory.
D
The theory contradicts an older theory.
33

Consider the unbalanced equation for the oxidation of aluminum._Al + _O2 _Al2O3Which sequence of coefficients should be placed in the blanks to balance this equation?

Question illustration
A
2, 3, 1
B
1, 3, 2
C
4, 3, 2
D
3, 2, 3
34

Which method for treating arthritis is an example of pseudoscience?

A
diet
B
drugs
C
exercise
D
magnets
35

Many pharmaceutical drugs are organic compounds that were originally synthesized in the laboratory. Which two scientific disciplines are bridged by pharmaceutical drugs?

A
chemistry and forensics
B
chemistry and medicine
C
biology and forensics
D
biology and criminology
36

Which statement best explains why the atomic theory developed efficiently?

A
Scientists ignored all previous knowledge about atoms.
B
Scientists had used creativity and the scientific method in their investigations.
C
Scientists had used a philosophical viewpoint as a method of investigation.
D
Scientists rarely repeated experiments to make sure the results were correct.
37

Which is the formula mass of Na2SO4?

A
119.06 amu
B
125.98 amu
C
142.05 amu
D
174.12 amu
38

What is the percent by mass of magnesium sulfate in MgSO4 · 7H2O?Use .

Question illustration
A
12.04%
B
48.83%
C
51.17%
D
86.98%
39

An entire group of elements was unknown when the periodic table was first developed because they were unreactive and no known compounds were composed of them. What most likely led to the inclusion of these elements in the periodic table?

A
the formation of a compound in the laboratory
B
new technology that showed how to identify one of the elements
C
improvements in instruments to measure small masses
D
more careful experiments to create synthetic elements
40

Consider the word equation.calcium hydroxide + hydrochloric acid calcium chloride + waterWhich is the corresponding formula equation?

Question illustration
A
Upper C a upper C l subscript 2 right arrow upper C a (s) plus upper C l subscript 2 (g).
Option A
B
Upper C a upper O (s) plus upper H subscript 2 upper O (l) right arrow upper C a (upper O upper H) subscript 2 (a q).
Option B
C
Upper N a upper O upper H (a q) plus 2 upper H upper C l (a q) right arrow upper N a upper C l (a q) plus 2 upper H subscript 2 upper O (l).
Option C
D
Upper C a (upper O H) subscript 2 (s) plus 2 upper H upper C l (l) right arrow upper C a upper C l subscript 2 (a q) plus 2 upper H subscript 2 upper O (l).
Option D

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