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

I have an eye but still cannot see.

Who am I?

If an electric train is travelling south, then which way is the smoke going?

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.

When I get multiplied by any number, the sum of the figures in the product is always me. What am I?

John was going on a jungle trip. He asked his wife to pack something to eat, something to drink and something to burn if he feels cold in the jungle. When John opens the backpack he found just one thing in the bag. What was it?

I am a normal creature, but I have five hands. I can even have more but even then I will be considered normal.

Who am I?

How can you write nineteen in a manner that if we take out one, it becomes twenty?

It comprises roots which nobody sees,
Much taller than those trees,
Up and up it goes,
Still it never grows?

The more of this there is, the less you see. What is it?