What is the Surname of Barbie Doll?

I have no doors but I have keys, I have no rooms but I have space, you can enter but you can’t leave! What am I?

Pronounced as 1 letter, And written with 3, 2 letters there are, and 2 only in me. I’m double, I’m single, I’m black blue and grey, I’m read from both ends, and the same either way. What am I?

Which alphabet letter is a question?

When monkey rotate the gear, which mark will be hit 1 or 2 ?

My cousin lives in one story house in Antarctica. His house is made the of-of sandstone. what is the color of stairs?

You know three triplets: Frank John and Wayne (need to return your money). Frank always tells the truth while John and Wayne always lie. You meet one of them on the road and can ask him a three-word question.
Which question, will you ask?

What word begins and ends with an E, but has only one letter?

Yesterday I fell from 30 feet high ladder but I don't get hurt. Why?

What number does the below three word/phrase identify and why?
1. Deck
2. Year
3. Singing in the Rain