Question 75: [Inorganic > Nitrogen & Sulphur]
Which statements are reasons why sulphur dioxide is used as a food preservative?
1 It is a reducing agent and therefore an anti-oxidant.
2 It prevents alcohols forming sour-tasting acids.
3 It does not smell and therefore can be used in more than trace quantities.
Reference: Past Exam Paper -June 2003 Paper 1 Q35
Solution 75:
Answer: B.
Statement 1 is true; a reducing agent is oxidised itself and therefore prevents other substance from being oxidises therefore an anti-oxidant.
Statement 2 is true because it prevents alcohols from being oxidised to acid as it is an anti-oxidant
Statement 3 is false because it does have a pungent smell
Question 59: [Inorganic > Nitrogen and Sulphur]
Which pollutant is formed in the internal combustion engine and, if not removed by the catalytic converter, may become involved in the formation of acid rain?
A C
B C8H18
C CO
D NO
Reference: Past Exam Paper -June 2003 Paper 1 Q19
Solution 59:
Answer: D.
A cannot be answer because carbon is not involved in acid rain
B cannot be because octane is not involved in acid rain
C cannot be because CO is not involved in acid rain it just kills people directly
D is the answer because both of NO and SO2 become involved in formation of acid rain.
Question 58: [Inorganic > Nitrogen and Sulphur]
Which reagent, when mixed and heated with ammonium sulphate, liberates ammonia?
A aqueous bromine
B dilute hydrochloric acid
C limewater
D acidified potassium dichromate(VI)
Reference: Past Exam Paper -June 2003 Paper 1 Q18
Solution 58:
Answer: C.
Test for the ammonium ion is adding a base then warming and then ammonia gas is produced therefore answer is C because limewater is Ca(OH)2 which is a base and when it reacts with an ammonium ion which ammonium sulphate it produces ammonia gas overall reaction is:
Ca(OH)2 + (NH4)2 SO4 = CaSO4 + 2NH3 + 2H2O.
Question 36:
[Inorganic > Nitrogen and Sulfur]:
Ammonia and chlorine react in the gas phase.
8NH3 +
3Cl2 à N2 +
6NH4Cl
Which statements are correct?
1 Ammonia behaves as a reducing agent.
2 Ammonia behaves as a base.
3 The oxidation number of the hydrogen changes.
Reference: Past Exam Paper – November 2002 Paper 1 Q36
Solution 36:
Answer: B.
The chlorine atoms change oxidation state from 0 to -1 which is reduction
hence ammonia has caused reduction and 1 is correct.
A base is a proton (H+)
acceptor and ammonia does this when becoming an ammonium ion in the ammonium
salt, thus 2 is also correct.
Oxidation number of hydrogen does not change; in
ammonia: +1, in salt: +1, thus 3 is incorrect and the correct option is B.
Question 19:
[Inorganic > Nitrogen and Sulfur]:
Which gas is present in the exhaust
fumes of a car engine in a much greater amount than any other gas?
A carbon dioxide
B carbon monoxide
C nitrogen
D water vapour
Reference: Past Exam Paper – November 2002 Paper 1 Q19
Solution 19:
Answer: C.
The composition of air is 79% nitrogen. When this enters a car’s
combustion chamber, it is mostly unreactive, and passes back out with the other
fumes.
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