I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

What is the Surname of Barbie Doll?

John was piloting a plane behind a car but was never able to overtake it. Why?

I am dry when I go inside, but wet when I am pulled outside.
The longer I am inside, the stronger I get
When I am completely out, I am wet and I literally sag
Who am I?

There are a number of books on a shelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?

Can you write down eight eights so that they add up to one thousand?

Before Mount Everest was discovered, what was the highest mountain in the world?

If a wheel has 54 spokes, how many spaces are there between the spokes?

When my father was 31 I was 8. Now he is twice as old as me. How old am I?

I know a nine-letter word having only one vowel.
Do you ?