correct use AM/PM or am/pm

[Mdenglish]

Hello there

Which of the following are wrong ?

1. am/pm
2. AM/PM
3. 07:30 AM (morning)
4. 07:30 am
5. 07:30 PM (evening)
6. 07:30 pm
5. 19:30 PM
6. 07:30
7. 7:30
8. 19:30

Thanks in advance,

mdenglish

[Benjamin]

AM and PM do not necessarily have to be in capitals if they are after a time, maybe capitals would avoid any confusion.

you do not have to put (morning) and (evening) after the time either.

but apart from that I'd say 5 (the second one) and 7 are wrong

5 because if you say 19:30 then you are using the 24 hour clock and it already implies it is afternoon so you don't have to put "PM"

7 isn't wrong but thats the only one where i have no idea if its morning or evening.

also...3-6 i'd say may be wrong because if you put a zero in front of the time it might again imply you are using the 24 hour clock.
so 3 and 4 should be 7:30am or 07:30
and 5 and 6 should be 7:30pm

I hope i cleared it up!!