C1H Edexcel PiXL Mark Scheme November 2014
Question / Answer / Additional Guidance1 (a) / Nitrogen = 78 (1)
Oxygen = 21 (1)
Argon = 0.9 (1) / Candidates do not need to write the percentage sign (%) as it is in the header of the table
1 (b) / Photosynthesis (1) by plants taking in carbon dioxide/releasing oxygen (1). Carbon dioxide from the atmosphere dissolved in oceans (1)
1 (c) / Any 2 from:
· Combustion
· Burning of fossil fuels
· Deforestation
· Removal of photosynthesis
· Burning of the trees
· Warming oceans causing them to hold less in solution
(2) / Accept higher levels answers
1 (d) / D by volcanoes (1) / Score 0 marks if more than one box is crossed
(Total for Question 1 = 9 marks)
2 (a) / A chalk (1) / Score 0 marks if more than one box is crossed
2 (b) / Any 3 from:
· Formed from pieces of other rocks/dead organisms/sea shells
· Layers of sediment build up
· These layers are compacted/squashed
· Cementation
(3)
2 (c) / Any 2 from:
· Construction
· Making glass
· Making cement
· Making steel
· Making iron alloys
(2) / Accept correct alternative answers
2 (d) / For, any 2 from:
· Employment
· Limestone is valuable
· Boost economy
· Can export limestone to other countries
· Limestone has many uses
(2)
Against, any 2 from:
· Noisy
· Dusty
· Eyesore
· Too much traffic
· Pollution
· Too much land used up
(2) / Maximum 2 marks for arguments for
Accept named use(s)
Maximum 2 marks for arguments against
Accept correctly named pollution gases
(Total for Question 2 = 10 marks)
3 (a) / C hydrochloric acid (1) / Score 0 marks if more than one box is crossed
3 (b) / A build-up of too much (hydrochloric) acid in the stomach (1) which causes pain in the tube leading to the mouth (1). This can be treated by an antacid (1) which neutralises the excess stomach acid (1).
3 (c) / Something that could be harmful/dangerous if not used properly (1)
3 (d) / 2HCl + CaCO3 → CaCl2 + H2O + CO2 (3) / 1 mark for formulae
1 mark for balancing
Allow = sign instead of →
(Total for Question 3 = 8 marks)
4 (a) / Contains hydrogen and carbon (1) only (1) / ‘Carbon and hydrogen molecules’ negate any marks
4 (b) / Any 3 from:
· From the remains of sea plants and animals
· Sediments buried on top of them
· In the absence of oxygen
· The remains no longer decayed
· Heat and pressure increased
(3)
4 (c) (i) / B fractional distillation (1) / Score 0 marks if more than one box is crossed
4 (c) (ii) / As the number of atoms in a carbon chain increase (1) the boiling point increases (1) because they have less bond between the carbon atoms to break (1)
(Total for Question 4 = 9 marks)
5 (a) (i) / 2 carbon atoms with a single bond (1)
6 hydrogen atoms with a single bond to the carbon atoms (1)
5 (a) (ii) / D they are saturated (1) / Score 0 marks if more than one box is crossed
5 (a) (iii) / 4 (1)
5 (b) / Bromine water (1) turns colourless (1)
5 (c) / Indicative content:
Cracking process
· Long chain alkanes are heated
· Long chain alkanes are broken up into smaller molecules
· Long chain alkanes are broken up into a smaller chain alkane and an alkene
· Cracking is a thermal decomposition reaction
Why cracking is needed for making petrol
· Shorter chain alkanes is used to make fuels, e.g. petrol
· Crude oil contains different mixtures of hydrocarbons
· Petrol has a higher demand than supply
· Oil companies have to crack long chain alkanes to make the supply match the demand / Mark the answer according to the levels below. Identify the level first of all, then award the top of the mark band if the student’s literacy is generally good or the bottom if there are many literacy errors.
Accept higher level answers.
Level / Level Description / Marks
0 / No relevant answer. / 0
1 / Simple explanation about why cracking is needed to make petrol or of the process of cracking. / 1-2
2 / A detailed explanation about why cracking is needed to make petrol or of the process of cracking.
or
A simple explanation about why cracking is needed to make petrol and of the process of cracking. / 3-4
3 / A detailed explanation about why cracking is needed to make petrol and of the process of cracking. Correct scientific terminology is used and the candidate’s answer flows well in a clear logical order. / 5-6
(Total for Question 5 = 12 marks)
6 (a) / Any 3 from:
· Conduct heat
· Conduct electricity
· Malleable
· Ductile
· Shiny
· Sonorous
(3) / Accept correct alternative answers.
6 (b) / Any 2 from:
· Low weight/mass
· Low density
· Does not corrode
(2)
6 (c) / C has a low reactivity (1) / Score 0 marks if more than one box is crossed
6 (d) / Indicative content:
What is an alloy?
· A mixture of metals
· To improve a metal’s properties for a specific use
How do alloys work?
· In a pure metal, all atoms are closely packed together and are the same size.
· In a pure metal, the layer of atoms can easily slide over each other.
· In an alloy, some of the atoms are of different sizes from different elements.
· Atoms can therefore not slide over each other as easily in an alloy.
· Alloys are therefore stronger and harder than pure metals.
What is a shape memory alloy?
· An alloy that returns to its original shape with a change in condition, such as temperature.
· Nitinol is an example of a shape memory alloy and can be used in the repair of a collapsed artery. / Mark the answer according to the levels below. Identify the level first of all, then award the top of the mark band if the student’s literacy is generally good or the bottom if there are many literacy errors.
Accept higher level answers.
Level / Level Description / Marks
0 / No relevant answer. / 0
1 / Simple explanation about what an alloy is or how it works. / 1-2
2 / An explanation of what an alloy is and how it works. / 3-4
3 / A detailed explanation about what an alloy is, how it works and an explanation of a shape memory allow. Correct scientific terminology is used and the candidate’s answer flows well in a clear logical order. / 5-6
(Total for Question 6 = 12 marks)
TOTAL FOR PAPER = 60 MARKS