Lab: Motion — Cumulative exam Answers

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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
2
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Why does the presence of lone pair electrons contribute to the polarity of a water molecule?

A
They allow the bonds between oxygen and hydrogen to be single.
B
They increase the partial positive charge on the oxygen atom.
C
They prevent the atoms from forming a linear molecule.
D
They counter the uneven pull on electrons between the atoms.
4

When ammonium chloride and water interact, less energy is released from breaking the bonds in the water and ammonium chloride than what is required to form the bonds of the new substance.

A
An endothermic reaction is occurring.
B
An exothermic reaction is occurring.
C
Energy is being released into the surroundings.
D
Energy escapes as light into the surroundings.
8

When a hammer strikes a compound formed by covalent bonds, what will most likely happen to the compound?

A
It will break into many pieces.
B
It will reform into a new shape.
C
It will spread out and then return to its original shape.
D
It will stay solid and resist the force of the hammer.
11

Alai records data about making a mixture of salt and water. Which best explains why Alai’s salt measurement is wrong?

Question illustration
A
It should be recorded in milligrams.
B
It should be recorded in millimeters.
C
It should be recorded in centiliters.
D
It should be recorded in centimeters.
12

A scientist wants to perform a controlled experiment to test the effect of rust on chemically treated iron. Which action would be most important to perform in a controlled experiment?

A
Design an experiment that is based on previously published results.
B
Expose the treated iron to the corrosive effects of the air.
C
Test a large piece of treated iron and a small piece of untreated iron.
D
Test a piece of treated iron and a piece of untreated iron under the same conditions.
13

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
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 best compares and contrasts how John Newlands and Dmitri Mendeleev organized elements?

A
Both Newlands and Mendeleev arranged elements according to their chemical properties, but only Newlands used atomic mass as well.
B
Both Newlands and Mendeleev arranged elements according to their atomic masses, but only Mendeleev used chemical properties as well.
C
Both Newlands and Mendeleev organized elements into groups, but only Newlands used a table with rows and columns.
D
Both Newlands and Mendeleev organized elements into a table with rows and columns, but only Mendeleev named different groups of elements.
16

Covalent bonds tend to make atoms more stable by helping them

A
fill up their innermost electron shell.
B
fill up their outermost electron shell.
C
empty out their innermost electron shell.
D
empty out their outermost electron shell.
17

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.
18

Which best describes a compound such as magnesium oxide?

A
an impure substance that is made up of two elements
B
a mixture of two uncommon substances
C
a mixture of two common elements
D
a pure substance that is made up of different elements
19

Which element is a halogen?

A
chlorine (Cl)
B
oxygen (O)
C
carbon (C)
D
radon (Rn)

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