I’m tall when I’m young, and I’m short when I’m old. What am I?

I add 5 to 9 and get 2. The answer is correct, so what am I?

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

Your mother’s brother’s only brother-in-law is asleep on your couch. Who is asleep on your couch?

I am an eight letter word and I am a computer terminology.
The second, third and fourth letters make an animal.
The fourth, fifth, sixth, seventh and eighth letters make a weapon.
The first, second, third and fourth letters can be taken as an outcome of any exam.
The fifth, sixth, seventh and eighth letter combine to form a high end typing software.

Can you tell 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?

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

I come in different shapes and sizes.
Parts of me are curved, other parts are straight.
You can put me anywhere you like,
but there is only one right place for me.
What am I?

A finger goes in me. You fiddle with me when you're bored. The best man always has me first. What am I?

I am 5 letters long.
My first two tell you who I am
My first 3 could be a medicine
My last three reversed could be a young boy.
My 4th, 3rd and 2nd in that order could be a fruit drink.
If you have me you may hang me round your neck
WHAT AM I ?