Free Printable Unit 3 B Practice Exam

1.

Two molecules of HBr collide and then for $H_2$ and $Br_2$ During the collision, the bonds in the HBr molecules are

a)

broken as energy is absorbed

b)

broken as energy is released

c)

formed as energy is absorbed

d)

formed as energy is released

2.

Which diatomic molecule is formed when the two atoms share six electrons?

a)

$H_2$

b)

$N_2$

c)

$O_2$

d)

$F_2$

3.

Which property is used to determine the degree of polarity between two bonded atoms?

a)

density

b)

electronegativity

c)

pressure

d)

temperature

4.

What is the number of electrons shared between the atoms of an $I_2$ molecule?

a)

7

b)

2

c)

8

d)

4

5.

What is formed when two atoms of bromine bond together?

a)

a monoatomic molecule

b)

a diatomic molecule

c)

a heterogeneous mixture

d)

a homogenous mixture

6.

Which pair of atoms is held together by a covalent bond?

a)

HCl

b)

LiCl

c)

NaCl

d)

KCl

7.

Which type of bond is formed between the carbon atom and the oxygen atom in $CH_3OH$

a)

ionic

b)

electrovalent

c)

polar covalent

d)

non-polar covalent

8.

Which substance contains nonpolar covalent bonds?

a)

$H_2$

b)

$H_2O$

c)

$Ca\left(OH\right)_2$

d)

CaO

9.

Which statement explains why a C-O bond is more polar than an F-O bond?

a)

At STP, carbon has a greater density than

fluorine.

b)

A carbon atom has more valence electrons than a

fluorine atom.

c)

the difference in electronegativity between

carbon and oxygen is greater than that

between fluorine and oxygen.

d)

The difference in first ionization energy between

carbon and oxygen is greater than that between

fluorine and oxygen

10.

Which formula represents a nonpolar molecule containing polar covalent bonds?

a)

b)

c)

d)

11.

Which formula represents a molecule with the most polar bond?

a)

CO

b)

NO

c)

HI

d)

HCl

12.

A molecule must be nonpolar if the molecule is...?

a)

linear

b)

neutral

c)

has ionic and covalent bonding

d)

has a symmetrical charge distribution

13.

Which formula represents a polar molecule containing polar covaent bonds?

a)

$H_2O$

b)

$CO_2$

c)

NaCl

d)

$Cl_2$

14.

Why is a molecule of $CO_2$ non-polar even though the bonds between the carbon atom and the oxygen atom are polar?

a)

the shape of the $CO_2$ molecule is symetterical

b)

the shape of the $CO_2$ molecule is symmetrical

c)

The $CO_2$ moleculele has a deficiency of electrons

d)

The $CO_2$ molecule has an excess of electrons.

15.

What is the chemical formula for sodium sulfate?

a)

$Na_2SO_3$

b)

$Na_2SO_4$

c)

$NaSO_3$

d)

$NaSO_4$

16.

What is the total number of different elements present in

NH_4NO_3

?

a)

7

b)

9

c)

3

d)

4

17.

What is the chemical name for

Na_2SO_{4\ }?

a)

sodium sulfite

b)

sodium sulfate

c)

sodium sulfide

d)

sodium thiosulfate

18.

Which compound has the strongest hydrogen bonding at STP?

a)

$H_2O$

b)

$H_2S$

c)

$H_2Se$

d)

$H_2Te$

19.

Which substance in this table below has the strongest intermolecular forces?

a)

HF

b)

HCl

c)

HBr

d)

Hi

20.

Which compound contains both ionic and covalent bonds?

a)

HCl(g)

b)

NaCl

c)

$NH_4Cl$

d)

$CCl_4$

21.

The equation below represents a chemical reaction

$2H_{2\ \left(g\right)+}O_{2\left(g\right)\rightarrow}2H_2O\left(g\right)\$ Compare the strength of attraction for electrons by a hydrogen atom to the strength of attraction by an oxygen atom within a water molecule.

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22.

What would the correct image for a water molecule look like?

a)

b)

23.

According to this reaction below, state the change in energy that occurs in order to break the bonds in the hydrogen molecules. Hint: Think of B.A.R.F

2H_{2\left(g\right)}+O_2\left(g\right)\rightarrow2H_2^{ }O\left(g\right)

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24.

Use the table to answer the question. Explain, in terms of charge distribution, why a molecule of hydrogen cyanide is polar. * This means the answer SHOULD have charge distribution to get credit.

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25.

According to the picture, describe, in terms of electrons, the type of bonding between the carbon atoms and the nitrogen atom in a molecule of methanamine.

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Unit 3 B Practice Exam

Total questions: 25

Worksheet time: 15mins

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