Page 55 - ACE YR IGCSE A TOP APPROACH TO CHEM

6 (a) Bleach wood pulp [1] or
(b) Kill bacteria [1] Oxides of nitrogen [1]
Nitrogen and oxygen react in the hot car engine.
(c) (i) A black solid is formed. [1] [1]
Sugar is sucrose, C H O . Water is removed Oxides of nitrogen dissolve in water to form acid rain.
11
12
22
from sucrose leaving the carbon. Carbon is a
black solid. or
(ii) Carbon [1] Lead compounds [1]
Burning of petrol containing lead
[1]
(iii) Any one from: [1] Lead compounds cause brain damage in children, kidney
• Fertilisers and nervous system damage in adults.
• Paint or
• Fibres and plastics Particulates [1]
Penerbitan Pelangi Sdn Bhd. All Rights Reserved.
• Soap Incomplete combustion [1]
• Detergents Particulates are tiny solid particles formed in an
• Car batteries incomplete combustion of fuels that contain carbon. It
7 (a) Glucose + oxygen ➞ carbon dioxide + water [1] is linked to respiratory problems and cancer.
(b) 6CO + 6H O ➞ C H O + 6O [1] 10 (a) Carbon dioxide [1]
2 2 6 12 6 2 (b) Ammonia [1]
(c) Methane [1] (c) Ethene [1]
Methane is a natural gas. It is also produced by (d) Neon [1]
animals from digestion and anaerobic respiration of (e) Nitrogen [1]
bacteria.
(d) Carbon dioxide is produced in combustion. [1] (f) Chlorine [1]
[1]
(g) Sulfur dioxide
Carbon dioxide absorbs heat. [1]
(h) Hydrogen [1]
(e) Any one from: [1] (i) Carbon monoxide [1]
• Plant more trees 11 (a) Burn sulfur [1]
• Reduce the burning of fossil fuels in the air [1]
• Use solar power or wind power S + O ➞ SO
• Capture greenhouse gases from chimneys 2 2
and bury them underground (b) Stop the growth of bacteria [1]
Buildings or statues made up of limestone, CaCO , (c) Purple [1]
3
will react with acid and release carbon dioxide.
to colourless [1]
(f) The reaction between limestone and acid rain Acidified potassium manganate(VII) is purple.
[1] (d) Sulfurous acid [1]
8 (a) Nitrogen [1] SO + H O ➞ H SO 3
2
2
2
Oxygen [1] (e) Corrode buildings / metal structures / limestone
Argon [1] statues or kill fish / plants [1]
(b) Nitrogen and oxygen react [1] because sulfur dioxide dissolves in water to
at high temperatures in car engines. [1] form acid rain [1]
Oxides of nitrogen dissolve in water to form 12 (a) Heat [1]
nitric acid. [1] Add water [1]
(c) Livestock agriculture / Fermentative digestion
in ruminant animals [1] (b) CaO + H O ➞ Ca(OH) [1]
2
2
Underground gas deposits [1] (c) It is a base. [1]
(d) Photosynthesis [1] Increase the pH of the acidic lake. [1]
Carbon dioxide is used during photosynthesis. (d) (i) Breaking down of a molecule [1]
9 Any three from: by heat [1]
Carbon monoxide [1] (ii) Ca(OH) ➞ CaO + H O [1]
Incomplete combustion [1] 2 2
Carbon monoxide is a poisonous gas. It is bonded with 13 (a) To remove sulfur dioxide [1]
haemoglobin and reduces the concentration of oxygen (b) Sulfur dioxide causes acid rain. [1]
in the blood. (c) A base [1]
or (d) Stays in the soil for a longer time. [1]
Sulfur dioxide [1] 14 (a) Oxygen [1]
Burning of fossil fuels containing sulfur [1] In photosynthesis, 6CO + 6H O ➞ C H O + 6O
Sulfur dioxide dissolves in water to form acid rain. 2 2 6 12 6 2

Answers 167

Answers.indd 167 3/4/22 3:54 PM