Name the three-letter word that can complete the below words:

A) L O _ _ _ E
B) E D U _ _ _ E
C) _ _ _ E R
D) _ _ _ T L E

Can you place six X (crosses) in below board without making three in a row in any way ?

There once were seven dwarfs who were all brothers. They were all born two years apart. The youngest dwarf is seven years old. How old is his oldest brother?

There is a square of a particular number which when doubled, becomes 7 more than its quarter.

Can you find the number?

13 decks of cards have been mixed. What is the minimum number of cards that must be taken out from the above-mixed cards to guarantee at least one 'four of a kind?

I speak without a mouth, and hear without ears. I have no-body, but I come alive with the wind. What am I?

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

What does this Rebus Picture means ?

I am under you when I am whole.
I shift above you if you remove the first letter.
I come all around you if you remove the second as well.

Can you tell me who I am?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?