AnswersCHS Chemistry AUnit Test

Unit Test — Unit test Answers

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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
2
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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
3

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.
4

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.
5

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.
6

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.
7

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
8

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
9

The compound FeCl3 is made of

A
three molecules of iron chloride.
B
one atom of iron and three atoms of carbon.
C
one atom of iron and three atoms of chlorine.
D
two atoms of iodine, one atom of iron, and one atom of carbon.
10

Which chemical equation is unbalanced?

A
C + O2 CO2
Option A
B
Sr + O2 2SrO
Option B
C
6H2 + 3O2 6H2O
Option C
D
H2 + H2 + O2 H2O + H2O
Option D
11

When sodium metal is added to water, an orange flame is observed on the metal surface. Based on this observation, what can best be concluded?

A
A physical change occurs because the metal gets smaller.
B
A chemical reaction occurs because the liquid becomes cloudy.
C
A chemical reaction occurs because heat and light are given off.
D
A physical change occurs because vapor is released into the air.
12

Which word equation shows hydrogen reacting with oxygen to form water?

A
oxygen + water hydrogen
Option A
B
hydrogen + oxygen water
Option B
C
oxygen + water hydrogen + water
Option C
D
hydrogen + water oxygen
Option D
13

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
14

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
15

Which type of reaction is represented by the generic equation AB + CD AD + CB?

Question illustration
A
combustion
B
decomposition
C
single replacement
D
double replacement
16

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
17

In which type of chemical reaction do two or more substances combine to form one substance?

A
synthesis
B
decomposition
C
single replacement
D
double replacement
18

A double replacement reaction can be best described as a reaction in which

A
a substitution takes place.
B
two atoms of a compound are lost.
C
ions are exchanged between two compounds.
D
electrons are exchanged between two atoms.
19

Which products would form if chlorine gas was bubbled through a solution of sodium bromide?

A
Na and BrCl
B
Na and BrCl2
C
NaCl and Br2
D
Na(Cl)2 and Br2
20

Considering the activity series given for nonmetals, what is the result of the below reaction? Use the activity series provided. F > Cl > Br > IBr2 + NaF

Question illustration
A
no reaction
B
Na + FBr2
C
NaBr + F2
D
Na2F + Br2

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