AnswersLA-Chemistry AElements, Compounds, and Mixtures

Elements, Compounds, and Mixtures Answers

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A teacher makes the following statement.“Gasoline boils at a relatively low temperature (about 150°C). The kerosene is removed at around 200°C, followed by diesel oil at 300°C and fuel oil at around 370°C.”What topic is the teacher most likely talking about?

A
distillation of a mixture
B
filtration of a pure substance
C
evaporation of a mixture
D
sorting of a pure substance
2
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Bromine, a liquid at room temperature, has a boiling point of 58°C and a melting point of –7.2°C. Bromine can be classified as a

A
compound.
B
impure substance.
C
mixture.
D
pure substance.
3

The table describes how some substances were formed.SubstanceDescriptionPFormed by boiling pure waterQFormed by combining three hydrogen atoms to every nitrogen atomRFormed by adding 5 g of sugar to 1 L of waterSFormed by compressing carbon under high pressureBased on the given descriptions, which substance is most likely a mixture?

A
P
B
Q
C
R
D
S
4

A chemist is studying an unknown substance and could break the substance into its elemental components only by using chemical means. Based on this observation, how should the unknown substance be classified?

A
impure substance
B
solution
C
mixture
D
pure substance
5

A solid precipitate is formed from the reaction of lead nitrate and sodium chromate. What would be the best method to separate this solid from the solution?

A
distillation
B
evaporation
C
filtration
D
sorting
6

The table shows the percentages of hydrocarbons that are found in a sample of crude oil.HydrocarbonsPercentageparaffins30naphthenes49aromatics15asphaltics6.0Based on the given information, what is the best classification for this sample of crude oil?

A
an element
B
a pure compound
C
a pure substance
D
a mixture
7

What can a drop of liquid mercury be described as?

A
a pure substance and a compound
B
an impure substance that is reactive
C
an impure substance that is unreactive
D
a pure substance and an element
8

Which sample is a pure substance?

A
zinc oxide
B
sugar dissolved in water
C
pond water
D
soil
9

Which cannot be chemically broken down into simpler substances?

A
compound
B
element
C
solution
D
mixture
10

A gravel can be broken down into different kinds of substances by physical processes. No chemical reactions are needed to separate different parts of gravel into pure substances. This is because gravel is a(n)

A
compound
B
element
C
homogeneous mixture
D
heterogeneous mixture

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