If eleven plus two equals one, what does nine plus five equal?

I am white when I am dirty, and black when I am clean. What am I?

I have an eye but still cannot see.

Who am I?

How many times can you subtract the number 5 from 25?

John enters a small room. The Door Closes.
When the door opens, John is in a larger room.

Explain?

I am a type of vehicle that has two wheels and is powered by humans. What am I?
Hint 1: You can ride me for exercise.
Hint 2: I am environment-friendly.

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

There is a five-letter word which has 3 consonants(all are same) and 2 different vowels.
Also, something wrong is associated with the word.

Can you name it?

He does not have any heart but still, He manages to live.
If you kill him, you will eventually die but yet you kill him.
He cannot run, who is He?

I sleep during the day and fly at night, but I have no feathers to aid my flight. What am I?