Thanks, these are helpful. :D
And regarding question 8, if the question did not state "a good
conductor of electricity", the answer can be both C and D right?
Because ethanol is soluble in water thus forms mobile ions..
In the polymerisation of ethene to form poly(ethene),
there is no change in
A. Boiling point
B. Density
C. Mass
D. Molecular
formula
(N2002 P1 40)
Answer is C but I don't get it.
Why mass? When it is polymerised, wouldn't the molecule become
larger and therefore increase in mass?
You're welcome, [e].Le-V. 
>>> And regarding question 8, if the question did not
state "a good conductor of electricity", the answer can be both C
and D right? Because ethanol is soluble in water thus forms mobile
ions. <<<
Not quite. Ethanol is soluble because it is able to form
hydrogen bonds with water molecules (approximately as strong as the
hydrogen bonds between water molecules). There are no ions produced
during the dissolving of ethanol into water, either mobile or
otherwise.
Note however, that the larger alcohols (eg. butanol, pentanol, etc)
are less soluble compared to ethanol, as the hydrocarbon chains are
non-polar ("fatty") and the hydrogen bonds from the
hydroxy group (-OH) in the alcohol are no longer sufficient to
drag the rest of the non-polar ("fatty") molecule to
dissolve into the water.
>>>
In the polymerisation of ethene to form poly(ethene),
there is no change in
A. Boiling point
B. Density
C. Mass
D. Molecular
formula
(N2002 P1 40)
Answer is C but I don't get it.
Why mass? When it is polymerised, wouldn't the molecule become
larger and therefore increase in mass? <<<
The mass of the TOTAL number of individual monomers
combined = the mass of the ADDITION polymer. (eg. 100 x 1g =
1000g)
If it were a condensation polymer (eg. polyamide, polyester,
etc), the mass of the polymer would be less than the total mass of
the individual monomers combined.
