Unit Test — Unit test Answers

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Which pair of substances would most likely result in the production of a gas when reacting with an acid?

A
litmus and methyl orange
B
base and salt
C
metal and carbonate
D
carbon dioxide and water
2
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What type of substance reacts with limestone (CaCO3) and produces carbon dioxide gas?

A
a neutral substance
B
a base
C
an acid
D
both an acid and a base
3

What happens to water when it freezes?

A
Its mass increases.
B
Its mass decreases.
C
Its density increases.
D
Its density decreases.
4

Which contributes to the polarity of a water molecule?

A
a linear shape along with strong covalent bonds
B
deflection of hydrogen atoms by lone pairs of electrons
C
no difference in the electronegativity of oxygen and hydrogen
D
hydrogen bond formation between water molecules
5

Soaps feel slippery on our hands because they dissolve the oil on our skin, decreasing friction.This is because soap contains

A
a neutral molecule.
B
a salt molecule.
C
an acid.
D
a base.
6

Which statement highlights a unique role of water in a biological system?

A
Organisms cannot use it to regulate their body temperature.
B
Few organisms can use it as a living environment.
C
It does not provide structural support to organisms.
D
It provides organisms a medium to transport materials.
7

Which describes a property of water that allows plants to transfer it from their roots to their leaves?

A
Water exhibits weak adhesion and cohesion, which allows capillary action to occur.
B
Water exhibits strong adhesion and cohesion, which allows capillary action to occur.
C
Water has low surface tension, which prevents capillary action from occurring.
D
Water has high surface tension, which prevents capillary action from occurring.
8

An unknown substance turns blue litmus paper to red. Which additional test could be used to confirm the substance’s identity?

A
It should turn phenolphthalein from colorless to pink because it is a base.
B
It should turn phenolphthalein from pink to colorless because it is a base.
C
It should turn methyl orange to orange because it is an acid.
D
It should turn methyl orange to red because it is an acid.
9

Which is a property of acids in aqueous solutions?

A
They feel soapy.
B
They taste bitter.
C
They increase the concentration of H+ ions.
D
They decrease the concentration of H+ ions.
10

Which is a characteristic of the polar water molecule?

A
a tetrahedral electron domain geometry with covalently bonded atoms
B
a tetrahedral electron domain geometry with ionically bonded atoms
C
a linear shape with polar covalent bonds
D
a linear shape with polar ionic bonds
11

Which example best shows that the chemistry of water is helpful to plants?

A
Water’s polarity produces a high density, which allows water to move to the leaves.
B
Water’s bent shape causes a slow passage of nutrients up to the leaves of plants.
C
Water’s polarity causes cohesion that pulls other water molecules up through a plant.
D
Water’s bent shape reduces its own passage through the cell membranes of roots.
12

The reaction below demonstrates which characteristic of a base?

Question illustration
A
the ability of bases to release sodium ions into solution
B
the ability of bases to release hydrogen ions into solution
C
the ability of a base to react with carbonate or bicarbonate
D
the ability of a base to react with a soluble metal salt
13

Which best explains the high surface tension of water?

A
its high density
B
its ion-dipole interactions
C
its adhesive interactions
D
its hydrogen bonding interactions
14

Water can resist a greater external force than ethanol can. Which statement best describes this difference?

A
Water has less capillary action than ethanol.
B
Water has greater capillary action than ethanol.
C
Water has lower surface tension than ethanol.
D
Water has greater surface tension than ethanol.
15

Which best explains why an iceberg floats?

A
Water expands and becomes denser when it freezes.
B
Water contracts and becomes denser when it freezes.
C
Water expands and becomes less dense when it freezes.
D
Water contracts and becomes less dense when it freezes.
16

Which pair of substances would most likely result in the production of a solid when reacting with a base?

A
litmus and phenolphthalein
B
soluble metal salt and carbon dioxide
C
acids and water
D
hydrogen ions and soaps
17

Look at the reaction below.Which substance is the acid in the reaction?

Question illustration
A
Mg(s)
B
H2(g)
C
MgSO4(aq)
D
H2SO4(aq)
18

Which statement best explains water’s ability to dissolve covalent compounds?

A
Water can dissolve polar covalent compounds through dipole-dipole interactions.
B
Water can dissolve nonpolar covalent compounds through hydrogen-bonding interactions.
C
Water can dissolve polar covalent compounds through ion-dipole interactions.
D
Water can dissolve nonpolar covalent compounds through dipole-dipole interactions.
19

H2SO4 is added to a large beaker of water. How is the solution different from the original water?

A
The solution turns blue litmus to red.
B
The solution turns phenolphthalein pink.
C
The solution has fewer hydrogen ions.
D
The solution has more hydroxide ions.
20

Which statement best describes how water’s properties relate to its functions in a human’s biological systems?

A
Water absorbs a lot of energy from the skin due to its high specific heat.
B
Water enters the body and provides support due to capillary action.
C
Water helps decrease the body’s density to allow it to float.
D
Water dissolves and transports nonpolar covalent compounds in the body.

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