How can you tell a raw egg from a hard-boiled egg?

Here is a mathematical expression that also secretly tells a movie name. What movie is that?

What is the Surname of Barbie Doll?

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.

What has no start, end, or centre?

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?

What does the below image rebus riddle means ?

There were five men at church, and it started raining while they were outside. The four that ran still got wet, but the one that was still stayed completely dry. Why did he stay dry?

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

I never stop running even when I standstill. If I am formed by joining two identical bodies together, can you guess who I am?