AnswersEO Night School Chemistry 7320AUnit Test

Unit Test — Unit test Answers

20 verified answers
1
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Which of these scenarios is most likely a chemical reaction?

A
A gas turns into a liquid as it releases energy.
B
A liquid becomes a gas as it absorbs energy.
C
Two white solids are added to a colorless liquid, and a colorless liquid remains.
D
Two colorless liquids are added together, and a colorless liquid and a green solid remain.
2
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What is the word equation for atoms of magnesium reacting with molecules of oxygen to produce magnesium oxide?

A
magnesium + magnesium oxide oxygen
Option A
B
magnesium + oxygen magnesium oxide
Option B
C
magnesium oxide + oxygen magnesium
Option C
D
magnesium + oxygen magnesium + oxygen
Option D
3

The equation below shows lithium reacting with nitrogen to produce lithium nitride.6Li + N2 2Li3NIf 12 mol of lithium were reacted with excess nitrogen gas, how many moles of lithium nitride would be produced?

Question illustration
A
4.0 mol
B
6.0 mol
C
12 mol
D
36 mol
4

The following balanced equation shows the formation of ammonia.N2 + 3H2 2NH3How many moles of nitrogen are needed to completely convert 6.34 mol of hydrogen?

Question illustration
A
1.02 mol
B
2.11 mol
C
12.68 mol
D
19.02 mol
5

Which evidence supports the idea that human activities influence atmospheric composition?

A
Humans drive cars that use fossil fuels.
B
Humans use more water to wash dishes by hand.
C
Humans are growing their vegetables in their backyards.
D
Humans are opening their windows instead of using their air conditioners.
6

Which statement best describes a mole?

A
It is used mainly for writing chemical formulas.
B
It is used for chemical equations that have reversible reactions.
C
It is used for directly comparing the amounts of substances.
D
It is used mainly for dealing with fluid substances.
7

The equation shows lead reacting with sulfuric acid to produce lead sulfate and hydrogen gas.Which type of chemical reaction does this equation represent?

Question illustration
A
synthesis
B
decomposition
C
single replacement
D
double replacement
8

How do greenhouse gases contribute to the warming of the Earth's atmosphere?

A
Greenhouse gases trap heat energy and keep the Earth's atmosphere warm.
B
Greenhouse gases trap light energy from the sun to warm the atmosphere.
C
Greenhouse gases trap all types of solar radiation to warm the atmosphere.
D
Greenhouse gases trap cold energy and keep the Earth's atmosphere warm.
9

Which characteristic best identifies a decomposition reaction?

A
a single compound as a reactant
B
a single compound as a product
C
an element and a compound as reactants
D
an element and a compound as products
10

Which statement best characterizes chemical reactions?

A
They always occur very quickly.
B
Their rates vary significantly.
C
Their rates are always slow.
D
They rarely occur in the natural environment.
11

Which must be the same when comparing 1 mol of oxygen gas, O2, with 1 mol of carbon monoxide gas, CO?

A
the mass
B
the volume
C
the number of molecules
D
the number of oxygen atoms
12

This formula equation is unbalanced.Pb(NO3)2(aq) + Li2SO4(aq) PbSO4(s) + LiNO3(aq) Which coefficient should appear in front of LiNO3 in the balanced equation?

Question illustration
A
1
B
2
C
3
D
4
13

Consider the balanced equation below. 2H2S + 3O2 2SO2 + 2H2OWhich option gives the correct mole ratios?

Question illustration
A
H2S:SO2 = 2:2 and O2:H2O = 3:2
B
H2S:SO2 = 2:3 and O2:H2O = 3:2
C
H2S:SO2 = 4:4 and O2:H2O = 5:4
D
H2S:SO2 = 4:6 and O2:H2O = 4:4
14

The balanced equation below shows the products that are formed when pentane (C5H12) is combusted. C5H12 + 8O2 5CO2 + 6H2OWhat is the mole ratio of oxygen to pentane?

Question illustration
A
1:6
B
6:8
C
8:1
D
5:8
15

When two substances are mixed together, a color change is observed. Does this mean that a chemical reaction has definitely occurred?

A
Yes because any change indicates a chemical reaction.
B
No because some physical changes produce color changes.
C
No because color changes are not indicators of chemical reactions.
D
Yes because color changes occur only when new compounds are formed.
16

Which statement describes a chemical reaction?

A
Reactants form products when atoms change state.
B
Products form reactants when atoms change state.
C
Reactants form products when atoms are rearranged.
D
Products form reactants when atoms are rearranged.
17

Which symbol can be used to indicate a chemical reaction that takes place in the presence of a catalyst?

A
350 degrees Celsius over a right-pointing arrow.
Option A
B
Upper P t over a right-pointing arrow.
Option B
C
0.5 a t m over a right arrow.
Option C
D
Delta over a right arrow.
Option D
18

Consider the chemical equation for the combustion of sugar._C6H12O6(s) + _O2(g) _CO2(g) + _H2O(l)Which sequence of coefficients should be placed in the blanks to balance this equation?

Question illustration
A
1, 6, 6, 6
B
6, 1, 6, 1
C
3, 3, 3, 6
D
1, 3, 3, 6
19

Which reaction will most likely take place based on the activity series?Li > K > Ba > Ca > Na > Mn > Zn > Cr > Fe > Cd > Ni > H > Sb > Cu > Ag > Pd > Hg > Pt

A
Pt + FeCl3
Option A
B
Mn + CaO
Option B
C
Li + ZnCO3
Option C
D
Cu + 2KNO3
Option D
20

What is the molar mass of fluorine, F2?

A
9.00 g/mol
B
18.00 g/mol
C
19.00 g/mol
D
38.00 g/mol

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