Worksheet on Elements, Compounds and Mixtures
Name : ___________________________ (
)
Date: 05042007
Class : _______________
Instruction: Answer all questions 1-9 below by filling the correct answer
in the given bracket.
1.
How many atoms are present in one molecule of sulphurous acid, H2SO3?
A
3
B
5
C
6
D
8
(
)
2.
A mixture ________.
A
has a fixed melting point.
B
has a fixed boiling point.
C
is made by a chemical reaction.
D
can be separated by physical methods.
3.
(
)
(
)
Which pair of substances are both mixtures?
A air; sea water
B diamond; vinegar
C ethanol; lime water
D water; air
4.
Which picture shows a compound made of two elements.
(
)
5.
Which element conducts electricity at r.t.p.?
A
Bromine.
B
Nitrogen.
C
Sulphur.
D
Sodium.
(
)
Which one of the following sets contains only one metal?
A
sodium
hydrogen
calcium
B
iron
oxygen
sulphur
C
copper
carbon
calcium
D
sulphur
magnesium copper
(
)
Which one of the following is an element?
A
Salt
B
Water
C
Air
D
Chlorine
(
)
6.
7.
8
The structural formula of glycerol is
Which statement about glycerol is not true?
A
B
C
D
9.
Its molecular formula is C3H8O3.
It contains three elements.
One molecule contains a total of 14 atoms.
Its molecular formula and empirical formula are different.
(
)
Which diagrams correctly show the molecules in ammonia, nitrogen and
hydrogen?
ammonia
nitrogen
hydrogen
A
B
C
D
(
)
Instruction: Questions 10-17 are structured questions. Fill your answers in the
blank spaces provided
10.
Choose your answers from the following list of substances.
air
chlorine
ice
calcium
gold
nitrogen
carbon dioxide
hydrogen
sea water
sugar
(a)
Name four elements.
(b)
Name two substances that are mixtures.
(c)
Name two substances that are single compounds.
(d)
Name one solid compound that contains the element carbon.
11(a) The formula of one molecule of nitric acid is HNO3.
12.
(i)
Name the elements present in nitric acid.
(ii)
What is the total number of atoms in one molecule of nitric acid?
Fructose is a sugar used in food. The structural formula of one form of
fructose is given below.
(i)
What are the elements present in fructose?
(ii)
What is the molecular formula of fructose?
(iii)
What is the empirical formula of fructose?
13.
A list of substances is given below.
Air
Water
Ethanol
Steel
Graphite
Petrol
Nylon
Protein
Chromium
Choose from the list one substance which
(i)
is an element.
(ii)
is a compound containing two elements only.
(iii)
is a compound containing nitrogen.
(iv)
is a mixture of compounds.
(v)
is a mixture of elements.
14(a) Substances can be classified as elements, compounds or mixtures. Put each
of the following into one of these classes.
(i)
Air.
(ii)
Ammonia.
(iii)
Ethanol.
(iv)
Iodine.
(b)
Mixtures of metals (e.g. brass) are commonly called :
15. The properties of some metal oxides are given in the table. All the oxides are
solid at room conditions.
name of oxide
copper(I) oxide
formula of
oxide
Cu2O
colour
effect of heating the oxide
red
remains red
lead(IV) oxide
PbO2
brown
mercury(II) oxide
HgO
red
potassium peroxide
K 2O 2
white
oxygen produced;
solid turns yellow
oxygen produced;
silvery liquid produced
remains white
Zinc oxide
ZnO
white
solid turns yellow when hot and
becomes white again on cooling
(a) Which of these oxides do not undergo a chemical reaction when heated?
...............................................................................................................................
[2]
(b) Suggest the identity of the silvery liquid formed from mercury(II) oxide.
..........................................................................................................................
16 (a) State three differences in the properties of elements that are metals and
elements that are non-metals. Write your answer in the table below.
Property
Metals
Non-metals
1
2
3
(b) Anhydrite is a white rock with the formula CaSO4.
Name the elements present in anhydrite and state whether each one is a
metal or a non-metal.
17. Fig. B shows some of the molecules in the air above an active volcano. For
example, a water molecule has the formula H2O and is shown by
in the
diagram. Write the formulas for the other molecules in the air above the
volcano.
.
Fig B
18.
Use examples :a mixture of iron filings and sulphur, a compound iron(II)
sulphide to illustrate the differences of properties between a mixture and a
single compound.
[4]
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