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WorksheetsChapter 21 review
Total questions: 30
Worksheet time: 23mins
Name
Class
Date
1.
Solve the problem: Al + O2 --> Al2O3
a)
4Al + 3O2 --> 2Al2O3
b)
2Al + 4O2 --> Al2O3
2.
Balance this equation, Ca + H2O --> CaO + H2
a)
Ca + 2H2O --> CaO + 2H2
b)
2Ca + H2O --> CaO + H2
c)
Its balanced as it is
d)
Cannot be balanced
3.
Name this reaction, Cl2 + 2KI --> I2 + 2KCl
a)
Synthesis
b)
Single Replacement
c)
Double Replacement
d)
Decomposition
4.
Name this reaction, CO2 + H2O --> H2CO3
a)
Decomposition
b)
Single Replacement
c)
Synthesis
d)
Combustion
5.
How many atoms of carbon (C) are in C6H12O6?
a)
3
b)
6
c)
12
d)
24
6.
How many Al atoms are in this compound? 4Al2O3
a)
2
b)
8
c)
6
d)
4
7.
___________________ are the elements are compounds that leave (are formed in) a chemical
reaction.
reaction.
a)
Polymers
b)
Bonds
c)
Reactants
d)
Products
8.
In a Chemical Reaction, the Law of Conservation of Mass states?
a)
Matter is never created but sometimes destroyed
b)
Matter is NOT created or destroyed.
c)
Matter is created and destroyed.
d)
Matter is sometimes created but never destroyed
9.
Solid magnesium, Mg, reacts with oxygen gas, O2, to form the solid magnesium oxide, MgO. Which equation is a balanced chemical equation for this chemical change?
a)
2Mg + O2 → 2MgO
b)
Mg + 2O → 2MgO
c)
Mg + O2 → MgO2
d)
Mg + O → MgO
10.
Which is NOT an example of chemical change?
a)
production of gas.
b)
change in color.
c)
change in size.
d)
transfer of energy.
11.
Which is a Synthesis Reaction?
a)
A + B ----> AB
b)
AB -----> A + B
12.
Is melting an object technically known as a chemical reaction?
a)
maybe?
b)
Yes
c)
No
13.
As the temperature of a material decreases, the particle moves ______ and their kinetic energy decreases
a)
faster
b)
slower
c)
stays the same
14.
Chemical reactions that release energy are known as ________________________.
a)
Endothermic
b)
Exothermic
c)
Boring
d)
Reactions
15.
Chemical reactions that absorb energy are known as ________________________.
a)
Endothermic
b)
Exothermic
c)
Boring
d)
Explosive
16.
A Precipitate forms
a)
when a gas is bubble through a liquid
b)
a lighter taper causes a gas to burn
c)
in a liquid or gas after a reaction and causes cloudiness (caused by a solid forming)
17.
A change in the size, shape, or state of matter.
a)
chemical change
b)
physical change
c)
chemical reaction
d)
electron change
18.
Which of the following is NOT an example of a physical change?
a)
crumpled paper
b)
pencil sharpening
c)
shrunken clothing
d)
sour milk
19.
In the equation, 2Mg + O2 = 2MgO, which are the reactants?
a)
Mg and O
b)
MgO
c)
Mg and MgO
d)
O and MgO
20.
Which of the following is a chemical change rather than a physical change
a)
boiling water at 100 C
b)
chopping up a piece of wood.
c)
cooking a cake
d)
ice carbon dioxide sublimating to gas
21.
Demonstrates the Law of Conservation of Matter and has the same number and the same type of atoms on both sides of the equation.
a)
balanced equation
b)
unbalanced equation
c)
coefficient
d)
subscript
22.
Balance this equation: H2 + N2 → NH3
a)
H2 + 4N2 → NH3
b)
H2 + 3N2 → 2NH3
c)
3H2 + N2 → 2NH3
d)
2H2 + 2N2 → 2NH3
23.
The large number in front of a chemical formula or compound is the ___________.
a)
coefficient
b)
product
c)
physical
d)
chemical
24.
The small number written below (after) a symbol.
a)
subscript
b)
physical
c)
unbalanced equation
d)
coefficient
25.
Which is the product? 2H₂ + O₂ ---> 2H₂O
a)
2H₂ + O₂
b)
2H₂O
26.
Gas evaporating is an example of a _____________ change.
**tricky!
**tricky!
a)
physical
b)
chemical
27.
Which of these is NOT a sign that a chemical change has occurred?
a)
The substance bends
b)
An unexpected color change
c)
A temperature change
d)
The formation of a precipitate
28.
The Law of Conservation of Mass states
a)
that matter exists in all states and reacts the same
b)
that matter can only be changed into new substances by introducing a catalyst
c)
that matter exists in the same state throughout any chemical change
d)
that matter cannot be created or destroyed and that the mass of the products must equal the mass of the reactants
29.
Balance this equation: H2 + N2 → NH3
a)
H2 + 4N2 → NH3
b)
H2 + 3N2 → 2NH3
c)
3H2 + N2 → 2NH3
d)
2H2 + 2N2 → 2NH3
30.
Balance the following chemical reaction: _CoBr3+_CsOH--> _Co(OH)3+_CsBr
a)
2,3,2,3
b)
3,1,3,1
c)
2,6,2,6
d)
1,3,1,3
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