Proffesor Dippet
In the room of requirement 7th floor
The riddles were used to unlock each chapter in Harry Potter and the Half-Blood Prince.
In the room where Hagrid is it's at the end of the level Tom Riddles Diary.
Answer: Tom riddles mother aka voldamorts mum. No, she is Merope Gaunt. Answer: There is no Merilyn in Harry Potter. There are some references to the wizard Merlin; perhaps you are confusing that.
Frank
If you mean the memory of professor slughorn telling tom riddle what horcruxes are, that was the sixth harry potter, the half blood prince.
The Pensieve.
THIS IS A SPOLIER FOR HARRY POTTER 7 tom riddles diary tom's ring slytherin's locket hufflepuff's cup ravenclaw's diadem voldemort's snake harry's scar
The charm "obliviate" is used in Harry Potter and the Chamber of Secrets by Proffessor Gilderoy Lockheart to erase Ron and Harry's memory. Unfortunately for him, he used Ron's broken wand and it backfired, erasing his own memory.
it shows harry and dumbledor looking into the memory pot
Tom Riddles Diary (Year 2 in the Chamber of Secrets)
Tom Riddle* and Harry both meet face to face in the Chamber of Secrets (book & film 2) when Harry is trying to save Ginny. However, earlier in the film there is a flash back into Riddle's diary, where Harry does see him, but its merely a memory, so Riddle doesn't see him.