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Unit 3 Practice and Review Part 1

Total questions: 10

Worksheet time: 7mins

Name
Class
Date
1.

Look at the following chemical equation.

8Ag2S → 10Ag + S8

What is true about this chemical equation?

a)

It is balanced because the products contain the

same number of sulfur (S) atoms as the reactants.

b)

It is unbalanced because the products contain

fewer silver (Ag) atoms than the reactants.

c)

It is balanced because the mass of the reactants is

equal to the mass of the products.

d)

It is unbalanced because the number of reactants is

less than the number of products.

2.

The equation shows the reaction between ammonia (NH3) and oxygen (O2).

__NH3 + __O2 → __NO + __H2O

In order to follow the law of conservation of mass, this

equation must have which set of coefficients, in order from

left to right?

a)

4, 5, 4, 6

b)

5, 4, 5, 4

c)

5, 4, 4, 5

d)

4, 6, 4, 5

3.

An equation is shown.

__Ag2O → __Ag +__O2

In order to follow the law of conservation of matter, this

equation must have which set of coefficients, in order from

left to right?

a)

2, 2, 2

b)

1, 2, 1

c)

3, 2, 3

d)

2, 4, 1

4.

__Fe + __Cl2 → __FeCl3

In order to follow the law of conservation of mass, this

equation must have which set of coefficients, in order from

left to right?

a)

3, 1, 2

b)

2, 1, 3

c)

2, 3, 2

d)

1, 3, 1

5.

4P + 5O2 → P2O5

What coefficient needs to be placed in front of the products

to make sure the law of conservation of matter is followed?

a)

1

b)

2

c)

3

d)

4

6.

H2 + O2 → H2O

What coefficients need to be placed in front of the reactants

and the product to make sure that the law of conservation

of matter is upheld?

a)

1,2,1

b)

1,2,3

c)

2,1,2

d)

2,3,2

7.

NaBr + Cl2 → 2NaCl + Br2

Is this a balanced chemical equation?

a)

No, because the mass of the reactants is less than

the mass of the products.

b)

No, because the reactants contain fewer molecules

than the products.

c)

Yes, because the reactants contain the same

number of chlorine (Cl) atoms as the products.

d)

Yes, because the mass of the reactants is equal to

the mass of the products.

8.

Zn + 2HCl → ZnCl2 + H2

Is this chemical equation balanced?

a)

Yes, because the mass of the reactants is equal to

the mass of the products.

b)

Yes, because the number of reactants is equal to

the number of products.

c)

No, because the mass of the reactants is greater

than the mass of the products.

d)

No, because the reactants contain fewer chlorine

(Cl) atoms than the products.

9.

Chemical equations must be balanced because

a)

the mass of the reactants is always greater than the

mass of the products.

b)

the mass of the products is always greater than the

mass of the reactants.

c)

mass can neither be created nor destroyed.

d)

mass is determined by a chemical reaction.

10.

Which of the following is correct about reactions?

a)

During nuclear reactions, atoms are rearranged

and all the atoms present in the reactants are

present in the products.

b)

During chemical reactions, atoms are rearranged

and all the atoms present in the reactants are

present in the products.

c)

During chemical reactions, alpha, beta, or gamma

radiation is emitted from the nuclei of the atoms

taking part in the reaction.

d)

During chemical reactions, the amount of energy

given off is always more than the energy given off in

nuclear reactions.