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i found these tips and they wer erally helpful so i thought id share em ! 
Paper 4 (Alternative to Practical) Tips
• When plotting graphs, you should be able to accurately plot to within one-half a small
square and the lines should go through the 0-0 point which should also be plotted if there
is data for it. However do NOT draw a line through the 0-0 point if it is clear that the trend
shows that the line is unlikely to go through this point.
• Practice extrapolating graphs. The extrapolated curve must follow the pattern of the line
or curve that is already there. If it is levelling off gradually, the extrapolated curve must
continue this levelling off.
• In the practical papers marks are not usually given for suggesting that you can separate a
solid from a solution by decanting off the solution. Filtration is the method that is
expected.
• Make sure that you know the difference between the tests for oxygen and hydrogen –
these are frequently muddled.
Hydrogen – Lighted splint – Pops (Hylight Pops).
Oxygen – Glowing splint – Relights (ogre)
• If you are asked to state a test for hydrogen do not just write down ‘Use the pop test’. This
description is too vague – it describes the result and not the test. It is far better to write
‘Insert a lighted splint into the test tube’.
• In describing colour changes which you expect to see when a metal such as zinc reacts
with a solution of copper sulphate, don’t write that the solution goes white. This is a
common error. You should state that the blue coloured solution looses it colour.
• You are given several diagrams of thermometers showing the temperatures as an
exothermic reaction proceeds and then have to plot a graph from the data. Make sure that
you always calculate the temperature change by taking away the initial thermometer
reading from each of the other readings. Don’t take the 3rd from the 4th, the 4th from the 5th
etc as so many of you do.
cheers :beer: :beer:
Paper 4 (Alternative to Practical) Tips
• When plotting graphs, you should be able to accurately plot to within one-half a small
square and the lines should go through the 0-0 point which should also be plotted if there
is data for it. However do NOT draw a line through the 0-0 point if it is clear that the trend
shows that the line is unlikely to go through this point.
• Practice extrapolating graphs. The extrapolated curve must follow the pattern of the line
or curve that is already there. If it is levelling off gradually, the extrapolated curve must
continue this levelling off.
• In the practical papers marks are not usually given for suggesting that you can separate a
solid from a solution by decanting off the solution. Filtration is the method that is
expected.
• Make sure that you know the difference between the tests for oxygen and hydrogen –
these are frequently muddled.
Hydrogen – Lighted splint – Pops (Hylight Pops).
Oxygen – Glowing splint – Relights (ogre)
• If you are asked to state a test for hydrogen do not just write down ‘Use the pop test’. This
description is too vague – it describes the result and not the test. It is far better to write
‘Insert a lighted splint into the test tube’.
• In describing colour changes which you expect to see when a metal such as zinc reacts
with a solution of copper sulphate, don’t write that the solution goes white. This is a
common error. You should state that the blue coloured solution looses it colour.
• You are given several diagrams of thermometers showing the temperatures as an
exothermic reaction proceeds and then have to plot a graph from the data. Make sure that
you always calculate the temperature change by taking away the initial thermometer
reading from each of the other readings. Don’t take the 3rd from the 4th, the 4th from the 5th
etc as so many of you do.
cheers :beer: :beer: