What Deficiency does the below rebus represent?

VIT_MIN

Can you spot the man between the coffee bean in the picture below ?

Only one color, but not one size,
Stuck at the bottom, yet easily flies.
Present in sun, but not in rain,
Doing no harm, and feeling no pain.
What is it?

I went to the bookshop and spent one-half of the money that was in my purse.

When I came out, I found that I had as many cents as I had dollars and half as many dollars as I had cents when I went in. Find the money in my purse when I entered the store.

Find the next number in the following series:
6, 14, 26, 98, __?

Twenty frogs are sitting on a log floating on the surface of a river. Two of them decide to jump off into the water.

How many frogs are there on the log at this moment?

Find the missing number in the sequence below:

What has many keys but can’t open a single lock?

A Scientist was fifty years old in the year 2000 but he was forty years old in the year 2010. How can this be possible?

PS: It has a logical answer.

What number does the below three word/phrase identify and why?
1. Deck
2. Year
3. Singing in the Rain