By removing one matchstick and adding one matchstick, can you convert the word "ZOO" to an animal name?

It's a protector.
It sits on a bridge.
One individual can see directly through it, while others wonder what it hides.

What is it?

I have no life, but I can die. What am I?

I always drive my customer away.

Who am I?

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

A 3 digit number is such that it's unit digit is equal to the product of the other two digits which are prime. Also, the difference between it's reverse and itself is 396.

What is the sum of the three digits?

You have three orange, two pink and five purple balls in the drawer beside your bed. There is no electricity and the room is entirely dark. How many balls must you take out to ensure at least one ball of each colour at least?

John is asked to stand behind Jacob and Jacob is asked to stand behind John. Both of them feel confused about it and don't know what to do?

But it is quite possible, do you know how?

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

How many runs at maximum can a batsman score in a normal one-day match? Consider the fact that the conditions are ideal and there are no No Balls, no Wide Balls and no Extras in that match.