No matter how little or how much you use me, you change me every month. What am I?

Pronounced as 1 letter, And written with 3, 2 letters there are, and 2 only in me. I’m double, I’m single, I’m black blue and grey, I’m read from both ends, and the same either way. What am I?

I am written with two letters.
I said with the one.
I usually am seen with the two.

Who am I?

I make a loud sound when I’m changing. When I do change, I get bigger but weigh less. What am I?

I am not a bull but I have horns.
I am not an ass but I have a pack saddle.
Wherever I go, I leave silver behind me.

Who am I?

The first person saw the bridge step on it and crossed,
the second person saw the bridge did not step on it but crossed,
the third person did not see the bridge did not step on it but crossed.
Who are these people?

Until it is measured, not known. Yet how you miss it when it has gone. What is it?

When you say goodbye, I am what you need to tie.
I come as a couple and go wherever you run.
Who am I?

I am a five-letter word and people eat me. If you remove the first letter I become an energy form. If you remove the first two letters, I am needed to live. Scramble the last three letters and I am a drink. What word am I?

12345 a famous South Indian actor
567 is a path in jumbled form
8 & 10 are same letters
9 is one among the first six alphabets.
WHO AM I?