What Deficiency does the below rebus represent?

VIT_MIN

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 ?

A pond had 60 fish, out of which, all but 20 died.
How many fishes are now present in that pond?

Two fathers and two sons went fishing one day. They were there the whole day and only caught 3 fish. One father said, that is enough for all of us, we will have one each. How can this be possible?

There is something which is always coming but never arrives?

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?

A little girl goes to the store and buys one dozen eggs. As she is going home, all but three break. How many eggs are left unbroken?

Through your logical capabilities, can you make 7 an even?

I have a five and a three-gallon jar. Assuming there is an infinite supply of water, how can I measure one-gallon water?

A quarter is one-fourth of a dollar but Mr. John has changed the equation as below :

DOLLAR * 4 = QUARTER

Can you replace each letter with a digit to make the above solution correct?