AS Physics - Electricity

So I'm a bit stuck on how to answer these question but I have had an attempt with one of them so far so please hint out to me anything that I need to include to elaborate my answers.

Questions
1a) Give the advantages of having the mains sockets in your house wired in series and in parallel.
1b) Write about voltage in series and in parallel and explain how these follow from a conservation rule.
1c) Describe the relationship between current and p.d. for this graph and discuss whether this graph obeys Ohms law.


My thoughts on answers:
1a) I am stuck on this because I don't know how to word this. Hints would be appreciated.
1b) Ok I know that the voltage in a series circuit add up the voltage of the battery (if that's how you should think of it) And the voltage in a parallel circuit across each branch is the same but I don't know how to explain the conservation rule part to these.
1c) The relationship is that they're not directly proportional. And the graph doesn't obey Ohm's law because it doesn't pass through the origin. I feel that my answer is lacking detail because I think I haven't discussed or described much about it.

Old style christmas tree lights with filament bulbs* were wired in series, if one failed or got unscrewed they all went out - because for components in series the current must be the same through every component... Can you see what this would mean for your domestic appliances if they were all in series?

more formally the number of charge carriers (electrons) going through any point of your series circuit is conserved, they don't leak away or increase in number. the number of charge carriers passing a point per unit of time is directly proportional to the current.

*does not apply to modern LED christmas lights (or some of the later models of xmas filament bulb which got around the problem)

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for the graph you can talk about the shape, is it curved or a straight line? what does that mean?
if straight, what is it's gradient? what does that mean?
where does it intersect an axis? what does that mean?

So could you say for 1a) That the advantages of having your mains sockets in parallel are the voltage remains the same and that the current is unchanged if one of them stops working whereas in series all of them would stop working. Could you say about there be less overheating?
1b) Maybe I'm dumb but I am having troubles getting into grasp of the hint you've given me. From what I know it seems you have described Kirchoff's law (correct me if I'm wrong).
Ok so for 1c) I realised that my class hasn't been taught about interpreting I-V graphs fully so I think I need a little bit more help. Ok I've talked about the graph being a straight line graph not passing through the origin. The gradient is the resistance and I don't understand why it intersects the x axis and what it means.

probably I shouldn't have talked about axis intersection cos if that's a graph of what I think it is, it runs along at zero current for low V and does pass through the origin, what you've got is one gradient for high V and a different gradient for low V.

but the graph that I've posted doesn't go through the origin.

I think it's supposed to through the origin horizontally, and whoever drew it didn't make that clear enough.

something's got to be happening at zero p.d.