Before I go any further, let me get one thing straight right now – there is only ONE way to spell separate, and that is …
SEPARATE.
Lesson 1: Kate G. of Sydney has a great way to remember how to spell this word:
Kate says, “Where’s the RAT??#! It’s in the middle!”
You spell this word sep-A-RAT-e
Lesson 2: Another easy way to remember how to spell separate is this:
There’s an A on each side of the R in “separate”.
Dan has emailed to say his teacher always reminded them there was A RAT in the middle of separate, and this great tip was also sent in by Kate [above].
Thanks Dan! (Oct 2000)
So there is only *one* way to spell separate … got it? Good 
Pssst! Do you have any tips or tricks to help you remember how to spell tricky words? If so, please let me know by filling in the Comments Form below.
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Hi Jackson,
Nice to hear from you again!
So now you know that ‘Whose who’ is wrong, and it should be ‘Who’s Who’.
As for no question mark, it could easily be a statement OR a question, so a question mark isn’t compulsory.
This is the correct statement from your three examples:
3. “Who’s who on the Titanic’s List of Passengers…”
Remember to say ALL the words including the missing bits, so it is actually:
3. “Who -IS- who on the Titanic’s List of Passengers…”
For more info, pop over to the WHOSE / WHO’S page >>
Hope this helps,
Cheers
Teena