Which is faster, Heat or Cold ? Explain.

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

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

What is at the end of a rainbow?

I never was there, I am always to be.
You have never ever seen me, not ever you will.
Yet I am the confidence of everyone.

Who Am I?

A man who was outside in the rain without an umbrella or hat didn’t get a single hair on his head wet. Why?

There is a brick of gold and a brick of iron in a boat (both 10-inch blocks), if they are both dropped into the water which will make the water level higher?

Can you find the key in the picture below?

Why Wine Glass Stem is so long?

One day, I thought of ways that can be used for creating a palindrome. So I decided that I will turn into a larger number by adding the reversed digits to the original number and keep doing it till I finally obtained a palindrome.

I am not sure if this process will always result in a palindrome eventually but I was able to produce a four-digit palindrome. Can you guess my starting number?