Aqa gcse chemistry 2017 unofficial mark schemeWatch
1a) Explain why the atomic number is the same for all of these atoms?
These are atoms of the same element with the same number of protons.
Why is the mass number different?
Each atom has different numbers of neutrons as they are isotopes.
Finish the sentence in terms of subatomic particles (3 marks): In the nucleus, there a protons each with a +1 charge. Therefore, due to this, the overall charge of the nucleus is positive.
Explain why each of these stages is done to cast iron.
Stage 1 (oxygen is blasted in) to remove carbon from the cast iron because the carbon reacts with the oxygen to produce carbon dioxide. Stage 2 is completed to make a strong alloy of the cast iron because the cast iron is too brittle.
Miller Urey question, why could their conclusion not be correct?
Not enough evidence
There are other theories which haven't been disproved yet: Meteors
What happens to the alkanes upon heating in the presence of a catalyst in the liquid paraffin question: Thermal decomposition/cracking
alkanes questions emulsions: Hydrophilic head attracted to water, hydrophilic tail attracted to oil. Oil droplets suspended in water 6 marker on quarrying, drilling and thermal decomposition: Carbon particulates cause global dimming. Carbon dioxide is a strong greenhouse gas and causes global warming. Impurities/ sulfur can react with oxygen to produce carbon dioxide which creates acid rain. Why was carbon dioxide removed before condensing? The carbon dioxide would freeze and so it was removed. Nitrogen can react with oxygen to produce nitrogen oxide which also contributes to acid rain... (? Debatable if this would be counted)