Good Riddles

Question: Swallowing one is fine.
Swallowing two together is fine.
But Swallow them separately and all shall fall.

What are they?

Question: Which is correct "The yolk of the egg is white" or "The egg yolk is white?"

Question: I am a small room,
but no life lives inside,
no matter what weather looms,
very cold my residents reside.
What am I?

Question: I am the only organ that named myself.What am I?

Question: Something different to show every week, but I'm still the same place.
If you're eating it's probably butter that you taste.

What am I?