Quickly Solve this riddle

7 - 4 + 3 * 0 + 1 = ?

What brings you down but never up?

I come in different shapes and sizes.
Parts of me are curved, other parts are straight.
You can put me anywhere you like,
but there is only one right place for me.
What am I?

You have 10 balls with you. A friend of yours out of nowhere asks you to place those ten balls in five lines such that each of the lines has exactly 4 balls on them. He needs to check your intelligence. Prove him by doing the task.

I cannot talk, but I always reply when spoken to. What am I?

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.

Find the missing number in the image below.

Spelt forwards I’m what you do every day, spelled backwards I’m something you hate. What am I?

I have branches, but no fruit, trunk or leaves. What am I?

How can you make a TV, a bed, a dog, and a car liquid?