If you say my name, I will no longer exist. What am I?

I am taken from a mine and shut up in a wooden case, from which I am never released, and yet I am used by almost every person. What am I?

O_er_t_o_

Complete the missing letters of the given word.

I am the fastest animal but cannot climb the tree. What am I?

A man and a dog were going down the street. The man rode, yet walked. What was the dog’s name?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

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?

I’m orange, I wear a green hat and I sound like a parrot. What am I?

I know a nine-letter word having only one vowel.
Do you ?

A wooden log balances equally on the scales when weighed with three-quarters of a pound and three-quarters of a wooden log.

Can you calculate the weight of the entire wooden log?