Examples of Marking Rules (Marking Scheme) for SPM Chemistry

I found a very informative article in Malaysia Student blog, discussing How to Score Well (1A) in Chemistry.
In one of the comment given by a visitor, there is a brief discussion
on some common mistakes often made by students. I found that it's very
useful and worth to share with. I've made some changes to the content.
The original article can be found in Malaysia Students blog.

Sample question:
1. State the possible observation when a few drops of ethene is added into a potassium manganate(VII) solution.

Sample Answer:
WRONG : Purple colour decolourize
CORRECT: Purple colour SOLUTION decolurize

2. Name the catalyse used in the estherification reaction between ethanol and ethanoic acid.

Sample Answer:
WRONG : Sulphuric Acid
CORRECT : CONCENTRATED Sulphuric Acid

3.
In the electrolysis of diluted copper(II) sulphate solution by using
carbon as the electrodes, state the observations in cathode and anode.

Sample answer:

Observation in cathode:
WRONG : Copper deposited at cathode
CORRECT : BROWN SOLID deposited at cathode

Observation in anode
WRONG : Oxygen gas released at anode
CORRECT : COLOURLESS GAS released at anode

(Comment:
Observation is what you see. You can only see a brown solid deposited
or a colourless gas is released, but you can't see what kind of solid
or gas it is. You know it is copper or oxygen base on your knowledge,
but not from the observation.)

4.
In the electrolysis of diluted copper(II) sulphate solution by using
copper as the electrodes, state the observations in anode.

Sample answer:
WRONG : Copper electrode corrodes
CORRECT : Copper electrode BECOMES THINNER

What
is given above is far from complete. All teachers and students are
welcome to share their knowledge on the marking scheme. Student are
also welcome to raise up their problems regarding how marks are given
in their exam paper.