AnswersWA-Physical Science BSpeed and Velocity

Speed and Velocity — Cumulative exam Answers

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1
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How would an electron shell model of an oxygen atom (O) appear after the atom has formed chemical bonds?

A
It would have six electrons in the outermost shell.
B
It would have six electrons in the innermost shell.
C
It would have eight electrons in the outermost shell.
D
It would have eight electrons in the innermost shell.
2
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Sudhi is studying the motion of a toy car. She places the car in the middle of a ramp and releases it.Which best describes the reference point in this scenario?

A
the top of the ramp
B
the bottom of the ramp
C
the ending position of the car
D
the starting position of the car
3

What is produced when calcium reacts with fluorine in a synthesis reaction?Ca + F2 ________

Question illustration
A
CaF
B
CaF4
C
2CaF
D
CaF2
4

Look at this image of a star cluster.

Question illustration
A
open
B
binary
C
globular
D
eclipsing
5

What do scientists know about the future of the universe?

A
what dark matter is made of
B
why the expansion of the universe is accelerating
C
that stars will eventually burn out causing the universe to become cold and dark
D
that galaxies spin much slower than they should based on visible matter
6

An atom of carbon (C) forms covalent bonds with two atoms of oxygen (O) to form carbon dioxide. How are the valence electrons of these atoms rearranged to form the bonds?

A
Electrons are transferred from the carbon atom to the oxygen atoms.
B
Electrons are transferred from the oxygen atoms to the carbon atoms.
C
Many valence electrons are shared between the atoms.
D
A few valence electrons are shared between the atoms.
7

Which most likely indicates a chemical change has occurred?

A
a solid substance becoming larger
B
a solid melting and becoming a liquid
C
a green liquid becoming a red liquid
D
a liquid freezing and becoming a solid
8

What is a main difference between a mixture and a pure substance?

A
A mixture is only a liquid, but a pure substance can be in any state.
B
A mixture looks the same throughout, but a pure substance does not.
C
A mixture can vary in composition, but a pure substance has a set composition.
D
A mixture can be made up of a single compound, but a pure substance cannot.
9

The symbol P represents the element phosphorus. This element’s atomic number is 15. How many protons and electrons are in a P–3 ion?

A
15 protons and 3 electrons
B
12 protons and 15 electrons
C
15 protons and 18 electrons
D
18 protons and 15 electrons
10

Which statement describes Earth?

A
It is an outer planet.
B
It is a gaseous planet.
C
It was formed from gas and dust.
D
It has a thick atmosphere of hydrogen and helium.
11

Which is the balanced equation for S8 + O2 → SO2?

A
S8 + O16 → 8SO2
B
S8 + O2 → S8 + O2
C
S8 + O2 → S8O2
D
S8 + 8O2 → 8SO2
12

Which is an example of a chemical change?

A
frying an egg
B
boiling water
C
melting butter
D
chopping onions
13

Which statement best explains how the mass of an atom is organized?

A
Most of the mass is contained in the nucleus.
B
The mass is spread evenly throughout the whole atom.
C
The mass is spread evenly throughout the electron cloud.
D
Most of the mass is contained in the electron cloud.
14

Which is a mixture?

A
sodium metal
B
chlorine gas
C
sodium metal and chlorine gas
D
sodium chloride (salt) and water
15

Which statement best describes the equation CaCO3 + 2HCl → CaCl2 + CO2 + H2O?

A
CaCO3 is a reactant; it is present before the reaction occurs.
B
CaCl2 is a reactant; it is present before the reaction occurs.
C
CO2 is a reactant because it is most likely a gas.
D
H2O is a reactant because it is most likely a liquid.
16

This is how platinum appears in the periodic table.

Question illustration
A
78
B
117
C
195
D
273
17

Carlos is making phosphorus trichloride using the equation below. 2P +3Cl2 _PCl3What coefficient of PCl3 would show that the law of the conservation of mass is represented in the chemical equation?

Question illustration
A
4
B
3
C
2
D
1
18

A cylinder at left with balls evenly spaced throughout the cylinder has an arrow leading to a cylinder at right cylinder with balls in a layer at its bottom.

Question illustration
A
condensation
B
boiling
C
sublimation
D
freezing
19

In an investigation, the atoms of a certain substance lose energy during a change of state. Before the change, the atoms are far apart and move constantly at high speeds and in all directions. After the change, the atoms are close together but are able to slide past one another.Use the diagram that shows changes of state between solid, liquid, and gas to answer the question.

Question illustration
A
L
B
N
C
O
D
P
20

Kenneth ran a marathon (26.2 miles) in 5.5 hours. What was Kenneth’s average speed? (Round your answer to the nearest tenth.)

A
0.2 mph
B
4.8 mph
C
5.5 mph
D
144.1 mph

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