Whose is That? - Possessive Terms

'... the parents of Sarah', presumably: in other words, hers.

' ... cars that belong to them'; in other words, theirs.

If, as we hope, it is coming to us, it is 'ours'.

Only 'mine' makes the most likely sense here.

Most likely, the car belongs to the people who are parking it so badly ('you', that we are talking to), so it'll be 'your car'.

Beware if your first language is French, because you may have thought ' ... son mari'. But in English, the difference between 'his' and 'her' depends on the gender of the owner, not the gender of the thing that they own. If someone has a husband (in the traditional understanding), she must herself be female/feminine, so the possessive will be 'her'.

Most animals are usually 'it' in English: since we don't have genders like many other languages do, we don't automatically think that all cats and dogs are somehow masculine, or all mice feminine. Obviously, if there is a 'mummy-animal' suckling her young (a chimpanzee, for instance), we might refer to her as 'she'; and if two great big males (lions, say; or deer) are fighting, we might well call either of them 'he'. But if the behaviour we're talking about is something that's not gender-specific, the animal will just be 'it' as far as English is concerned.

If this is the female bird who produced the chicks, then we will need 'she' and 'her' for talking about her (see previous hint, at Question 7).

'One' has its own possessive form. We may not know whether the 'one' happens to refer to a man or a woman, so neither 'his' nor 'her' would necessarily be right. Nor do we use 'their' in this context (though you may quite often hear 'Who's left their coat on my chair?' ... when it may be fairly clear from the style of coat, whether the owner was male or female; and 'Someone's put their umbrella in the wash-hand-basin').

It can't be 'ours' (with the old man speaking, and including himself in what he says) if he knows he will no longer be alive tomorrow; 'his' makes no sense if we don't know what other man he means (though it might well have been his son).
It is just one of those unfortunate accidents of language that 'mine' has several meanings: 'mine' = 'belonging to me' ('If yours is broken, let me lend you mine'); 'mine' = a pit from which coal or other minerals (e.g. gold) are dug out; 'mine' = a military explosive (and hence the metaphorical expression, 'Don't raise that topic in conversation, it's a minefield' ... i.e. if you bring it up to talk about, there might be an 'explosion' of anger from someone who feels strongly about it).