Beaconhouse School System
(Cantt Campus, Lahore)
Name: …………………………………….___ Class Test: Bonding & Purification Techniques Class/Section:……..………..
Date :____/___/__ Total Marks: 30 Time Allowed: 40Min
PART I
1. A paper chromatography experiment is carried out to separate and identify the mixture of
amino acids produced from the hydrolysis of a protein.
Which apparatus is needed?
A chromatography paper, locating agent, marker pen, solvent
B chromatography paper, locating agent, pencil, ruler, solvent
C chromatography paper, locating agent, ruler, solvent, thermometer
D chromatography paper, locating agent, pencil, solvent, thermometer
2. Diamond and graphite are two different forms of the element carbon. They each have different
uses. Which row is correct?
3. Which diagram shows the outer electron arrangement in calcium fluoride?
4. Two statements about metals are given.
1 Metals contain a lattice of negative ions in a ‘sea of electrons’.
2 The electrical conductivity of metals is related to the mobility of the electrons in the structure.
Which is correct?
A Both statements are correct and statement 1 explains statement 2.
B Both statements are correct but statement 1 does not explain statement 2.
C Statement 1 is correct and statement 2 is incorrect.
D Statement 2 is correct and statement 1 is incorrect.
5. Which process is involved in all of the following?
1 obtaining copper(II) sulfate crystals from aqueous copper(II) sulfate
2 obtaining ethanol from the fermentation of glucose
3 obtaining nitrogen from liquid air
A crystallisation
B evaporation
C filtration
D fractional distillation
6. An element with a high melting point forms an oxide that is gaseous at room temperature.
Which type of structure or bonding is present in the element?
A giant covalent
B ionic
C metallic
D simple molecular
7. Which statement explains why aluminium is malleable?
A Aluminium has layers of cations that can slide over one another.
B Aluminium has layers of electrons that can slide over one another.
C Aluminium has weak bonds between protons and a ‘sea of electrons’.
D Aluminium is covered with a layer of unreactive aluminium oxide.
8. The results of a paper chromatography experiment are shown.
X is an aqueous solution of a salt of a Group I element.
Y is an aqueous solution of a salt of a transition element.
9. Magnesium oxide has a high melting point. It is used to line the inside of furnaces that operate at
high temperatures.
Why does magnesium oxide have a high melting point?
A It has metallic bonds.
B It has strong forces between its molecules.
C It is a simple molecular substance.
D It is an ionic compound.
10. What is the dot-and-cross diagram for NCl 3?
PART II
1. A molecule contains four amino acid units. These amino acid units are linked in the same way as in
a protein. A sample of this molecule is hydrolysed. The resulting colourless solution is spotted onto
chromatography paper. The paper is placed into a suitable solvent. A diagram of the final
chromatogram is shown.
position of solvent front
position of original
initial line spot
of hydrolysed sample
(a) Suggest why the initial line is drawn in pencil and not ink.
...........................................................................................................................................
........................................................................................................................................[1]
(b) Draw a line on the diagram of the chromatogram to show the depth of solvent into which the
paper is placed. [1]
(c) Suggest how the chromatogram needs to be treated to make the spots visible.
...........................................................................................................................................
........................................................................................................................................[1]
(d) What effect does hydrolysis have on the sample of the molecule?
............................................................................................................................................
.......................................................................................................................................[1]
(e) Suggest a reason why only three spots are detected on the final chromatogram.
............................................................................................................................................
.......................................................................................................................................[1]
(f) The Rf values of some amino acids, in the solvent used for this experiment, are shown.
amino acid Rf value
alanine 0.38
leucine 0.73
phenylalanine 0.68
arginine 0.20
valine 0.61
(i) State how an Rf value is calculated.
...........................................................................................................................................
...........................................................................................................................................
.......................................................................................................................................[2]
(ii) State which one of the amino acids, listed in the table, is present on the chromatogram.
Your answer should include measurements from the diagram and a calculation to justify
your decision.
.......................................................................................................................................[2]
[Total: 9]
2. A student prepares propanoic acid by oxidising an alcohol with acidified potassium
dichromate(VI) in the apparatus shown below.
A
water out
water in
an alcohol
+ aqueous acidified
potassium
heat dichromate(VI)
(a) (i) Name and give the formula of the alcohol used to prepare propanoic acid.
alcohol ......................................................................................................................
formula ................................................................................................................ [2]
(b) Name apparatus A and suggest why it is used in this
preparation. name .....................................
use ...........................................................................................................................
............................................................................................................................. [2]
(d) Explain which is the better choice to heat the flask; an electric heater or a Bunsen
burner.
..................................................................................................................................
..................................................................................................................................
............................................................................................................................. [1]
(e) When all the alcohol has been oxidised the student uses the apparatus shown below to produce a
pure sample of propanoic acid (boiling point, 140 °C).
thermometer
water out
water in
receiver
reaction mixture
heat
(f) Water will initially distil over into the receiver flask.
What is the reading on the thermometer when the water is distilling over?
............................................ °C [1]
(g) How does the student know when propanoic acid begins to distil over?
............................................................................................................................. [1]
(ii) Why should the top of the receiver flask remain open?
............................................................................................................................. [1]
[Total: 8]
3. The table shows some of the properties of the elements in Group III of the Periodic Table.
proton (atomic) atomic radius melting point
element
number / nm / °C
B 5 0.080 2306
Al 13 0.125 660
Ga 31 0.125 30
In 49 0.150 157
Tl 81 0.155 304
Nh 113
Nihonium, Nh, has only recently been discovered.
It has not been possible to measure its atomic radius and melting point because it is too
radioactive.
Estimate the atomic radius of Nh.
.....................................................nm [1]
(ii) Explain, using data from the table, why it is difficult to estimate the melting point of
nihonium.
...........................................................................................................................................
..................................................................................................................................... [1]
(b) Boron has a giant covalent structure. Explain
why boron has a high melting point.
...................................................................................................................................................
............................................................................................................................................. [1]
[Total: 3]
