Dear Imraan:
Here come some help - even as I took my last chemistry course
53 years ago, and I was not studying for a PhD in chemistry (but in
engineering), so things such as polar bonds and so on I never learned.
But on many things I have some ideas, the others I will just "pass".
Question 1: a crystal is characterized by having its atoms
staying (or vibrating around) at fixed locations, which are the
"lattice points". The smallest group of such points, which by repe-
titions give the whole crystal, is the "unit cell".
Q2: I think that in the sense of "chemical reaction", metals
do not react with each other, but maybe some "bonding" reaction or so
are possible.
Q3,4: pass
Q5: A vapor (vapour) is "saturated" if it is in contact and
equilibrium with its liquid phase. (If you would expand it, more
liquid would evaporate).
Q6: No.
Q7: pass
Q8: not exactly, but with good approximation, Yes. Example: any
gas which has expanded enough; practically, if it is far from its
point of liquefaction, for exaple air.
Q9: pass
Q10: calculating the amount of sulphate molecules per liter is
straightforward, but I don't know the degree of ionization.
Q11: pass
Q12: As far as I know, ions exist only in solution, hence are
no solid.
Q13: pass, except that "van der Waals" forces are those when
the volume of the molecules is NOT negligeable with respect to
the total volume of a gas, hence seems not to have anything to do
with diamond or carbon.
Good luck!