What has one letter and starts with an E?

I am a five-letter word and comprises two different vowels and three same consonants. I am so strong that I can spoil your entire work.

Can you find out who am I?

Pronounced as one letter,
And written with three,
Two letters there are,
And two only in me.
I am double, I am single,
I am black blue and grey,
I am read from both ends,
And the same either way.

I make two people out of one. What am I?

You knock a Table over in the library, and suddenly 20 eyes are looking at you.

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

If eleven plus two equals one, what does nine plus five equal?

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?

My thunder comes before the lightning; my lightning comes before clouds; my rain dries all the land it touches. What am I?