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CHEMICAL REACTIONS

Total questions: 50

Worksheet time: 12hrs 33mins

Name
Class
Date
1.

A substance that is formed as the result of a chemical reaction is a __________________

a)

Product

b)

Reactant

c)

Starters

d)

Enders

2.

Which of the following is an example of a chemical change?

a)

water freezes to form ice

b)

sugar dissolves in water

c)

gasoline burns in a car engine

d)

a piece of metal expands when it is heated

3.

A change in the shape of an object is an example of _________________.

a)

a chemical change

b)

energy

c)

an endothermic change

d)

a physical change

4.

Which one shows that a chemical reaction has occurred?

a)

dissolving

b)

melting

c)

formation of a gas

d)

bending

5.
What type of change occurs when a new substance is formed that has different properties from the original substances?
a)
chemical change
b)
nuclear change
c)
physical change
d)
mutation
6.
a copper penny turning greenish after a few years.
a)
Chemical Change
b)
Physical Change
7.
In a ___________change, a substance changes into a different substance.
a)
Physical
b)
Chemical
8.

What is the BEST definition of a chemical reaction?

a)

A change in matter that produces one or more NEW substances

b)

When two things combine and EXPLODE.

9.

True or False: In a complete chemical equation, there must be the same number of atoms of each element on the reactants and products side.

a)

True

b)

False

10.

Which of the following 2 are chemical reactions?

a)

sugar dissolving in water

b)

water turning into steam

c)

burning wood

d)

mixing baking soda and vinegar

e)

tearing paper

11.
an atom or molecule which has gained or lost one or more of its valence electrons
a)
Covalent Bond
b)
Chemical Formula
c)
Ion
d)
Compound
12.
a substance formed when two or more elements are chemically bonded together
a)
Element Soup
b)
Pure Element
c)
Ion
d)
Compound
13.
a process or reaction in which the system absorbs energy from its surroundings; usually, but not always, in the form of heat
a)
Endothermic Reaction
b)
Exothermic Reaction
c)
Diffusion
d)
Fission
14.
a chemical reaction that releases energy by light or heat
a)
Endothermic Reaction
b)
Exothermic Reaction
c)
Diffusion
d)
Fission
15.
In an endothermic reaction, heat is ...
a)
taken in or absorbed
b)
given out or released 
16.
Exothermic reactions...
a)
Absorb energy
b)
Release energy
c)
Release Color
d)
Absorb Color
17.
The blue numbers in the image below represent ________
a)
I don't know, and don't want to try
b)
coefficients
c)
subscripts
d)
none of the answers are correct
18.
What is this ?
a)
a chemical reaction
b)
a mathematical equation
c)
a chemical equation
19.

The mass conservation law says

a)

During a chemical reaction, atoms are destroyed. The number of atoms don't remains constant throughout the reaction.

b)

During a chemical reaction, atoms are created. The number of atoms remains constant throughout the reaction.

c)

During a chemical reaction, atoms are neither created nor destroyed. The number of atoms remains constant throughout the reaction.

20.
The right side of the equation below is called the
a)
products
b)
reactants
21.
The only way you can be certain that a chemical reaction has occured is by? 
a)
Light has been emitted 
b)
a colour change has occurred 
c)
bubbles appear 
d)
identifying one or more new chemical products 
22.

What is the ratio of potassium atoms to oxygen atoms in K2O?

a)

1:2

b)

2:1

c)

1:1

d)

2:2

23.
Is burning a campfire a chemical or physical change?
a)
Chemical
b)
Physical 
24.
Which statement is not a description of a chemical reaction?
a)
A solid is dropped into a beaker of liquid and a gas is released.
b)
Two liquids are mixed in a beaker and a solid forms at the bottom of the beaker.
c)
A solid is dropped into a beaker of liquid and an explosion occurs.
d)
A liquid is heated in the sun and half of it evaporates.
25.
In the reaction methane + oxygen turns into carbon dioxide + water, the methane and oxygen are called _______________.
a)
reactants
b)
products
c)
neutrals
d)
energizers
26.
The force that holds 2 atoms together is called a ________________.
a)
Chemical Reaction
b)
Chemical Bond
c)
Diatomic Chemical
d)
Glue
27.
Is burning wood a chemical or physical change?
a)
chemical
b)
physical
28.
A change in the size, shape, or state of matter.
a)
chemical change
b)
physical change
c)
chemical reaction
d)
electron change
29.
Which of the following is NOT an example of a physical change?
a)
crumpled paper
b)
pencil sharpening
c)
shrunken clothing
d)
sour milk
30.
Evidence of a chemical reactions is anything that shows - 
a)
a new substance has formed
b)
a solid dissolved in a liquid
c)
interaction between 2 gases
d)
a change in the state of matter
31.
If you break a piece of glass, the shape of the glass changes, but the properties in the fragments remain the same. Which of the following has occurred?
a)
A chemical change.
b)
A temperature change.
c)
A phase change.
d)
A physical change.
32.
Which observation would most likely indicate that an endothermic reaction has occurred?
a)
a color change
b)
the production of gas bubbles
c)
an increase in temperature
d)
 a decrease in temperature
33.
A balanced chemical equation is one in which:
a)
the number of atoms of each element is the same in both the reactants and the products.
b)
the same compounds are present in both the reactants and the products.
c)
the reactants and the products have equal densities.
d)
 the reactants and the products have equal volumes.
34.

According to the Octet Rule, atoms of elements react with each other in order to attain ____ electrons in their outermost energy level or shell.

a)

2

b)

4

c)

6

d)

8

e)

10

35.

What is the best definition of valence electrons?

a)

The outermost electron NOT involved in chemical reactions

b)

The innermost electrons involved in chemical reactions

c)

The outermost electrons involved in chemical reactions.

d)

The innermost electrons NOT involved in chemical reactions

36.
How many valence electrons are elements trying to reach in their outer shells?
a)
1
b)
2
c)
5
d)
8
37.

Anions have a ________ charge.

a)

positve

b)

negative

c)

neutral

38.

Cations have a __________ charge.

a)

positive

b)

negative

c)

neutral

39.

How many atoms make up one molecule of laughing gas?

a)

1

b)

2

c)

3

d)

4

40.

In a chemical reaction or change a new substance is not created.

a)

true

b)

false

41.
What is a reactant?
a)
The starting substance
b)
The ending substance
42.
What is a product?
a)
The starting substance
b)
The ending substance
43.
Using the following chemical reaction
Hydrogen + Oxygen --> water
Identify the reactant(s).
a)
Hydrogen and Oxygen
b)
water
44.
Using the following chemical reaction
Hydrogen + Oxygen --> water
Identify the product(s).
a)
Hydrogen and oxygen
b)
water
45.
Which of the following are NOT signs that a chemical reaction occured?
a)
the properties changed
b)
bubbles of gas formed
c)
color stays the same
d)
smells different
46.
What is a precipitate?
a)
a change in color 
b)
a change in temperature
c)
a solid formed
d)
a gas formed
47.
What is a pure substance that cannot be broken down into any other substance by physical or chemical means. Ex: Gold, Silver, Oxygen, & Nitrogen
a)
element
b)
compound
c)
mixture
d)
salad
48.
What is a  pure substance made of two or more elements chemically combined in a set ratio. Ex: CO2 has a set ratio of 1:2, meaning for every one carbon atom there are two oxygen atoms.
a)
element
b)
compound
c)
mixture
d)
salad
49.
What is matter
a)
Anything which is solid
b)
Anything that takes up space and has mass
c)
when something is wrong
50.
The Law of Conservation of Matter says
a)
Matter can be created, but not destroyed
b)
matter can be destroyed, but not created
c)
matter cannot be created or destroyed

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