What have one eye but still cannot see?

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?

If you say my name, I will no longer exist. What am I?

What has one letter and starts with an E?

I am a type of food that is often found in the fridge and can be white in colour. What I am?
Hint 1: I am a dairy product.
Hint 2: You can spread me on the bread.

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

Can you spot what's wrong with the following sentence?

PETER WAS ANGRY AT
HIMSELF BECAUSE HE
ACCIDENTALLY LEFT THE
THE KEYS TO HIS CAR
AT HIS FRIEND'S HOUSE.

Known by all without exception, Forever here, for your protection, Sometimes strong, sometimes weak, Right after the night I come - hot and chic. And while millions of miles away, I always get to you, I find my way. No life around could do without me, Can you guess what I might be?

I live in a bowl. I can swim. I have a tail. I also have fins and big eyes. What am I?

How many sides does a circle have?