Many have heard it, but nobody has ever seen it, and it will not speak back until spoken to. What is it?

You have a basket containing ten apples. You have ten friends, who each desire an apple. You give each of your friends one apple.
Now all your friends have one apple each, yet there is an apple remaining in the basket.
How?

There was a greenhouse.
Inside the greenhouse, there is a white house.
Inside the white house, there is a red house.
Inside the red house, there are lots of babies.

What is It?

Eight of us go fourth, not back, to protect our king from an attack. What are we?

A shepherd had 18 sheep, out of which, all but ten died.

Can you tell us how many sheep was he left with?

Replace the question mark in the picture below.

Can you decipher the two rows to find the hidden word?

ENEMY = 2 * LINK
LINK + 2 = HELL

Then what will be TAXI + HELL? Select from the options below:
a) ROTTEN
b) DANGER
c) HEAVEN
4) MORTAL

What occurs twice in a week, once in a year but never in a day?

An infinite number of mathematicians are standing behind a bar. The first asks the barman for half a pint of beer, the second for a quarter pint, the third an eighth, and so on. How many pints of beer will the barman need to fulfill all mathematicians' wishes?