What Deficiency does the below rebus represent?

VIT_MIN

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?

Count the number of triangles in the given picture.

Kohli and Dhoni decided to have a paintball match.
Kohli told Dhoni, "Sir it is not right as you got thrice the paintballs I have".

Dhoni instantly gives Kohli 10 hit paintballs.
Kohli replied, "Sir, I believe you still have twice the paintballs than I have".

Dhoni gives "?" more paintballs to Kohli.
Kohli replied, "Sir it is even now, Let us have a match".

What is "?".

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

Solve the mathematical equation in the picture below.

I’m light as a feather, yet the strongest person can’t hold me for five minutes. What am I?

The following four words might seem abrupt to you. But you can make them meaningful by just adding vowels.
RDSH
GGPLNT
TMT
NN

Hint: All of them are vegetables.

What can you hold in your right hand, but never in your left hand?

What is more useful when it is broken?