There are are five things wrong with this sentence; only geniuses will be able to to spot all of the mitstakes

Name a key which is hardest to turn.

What word is represented by this rebus?

Find the next number in the series below

21 32 54 87 131 ?

Count the number of squares in the picture below.

Take away the whole and some still remain. What is it?

You walk into a room that contains a match, a kerosene lamp, a candle and a fireplace. What would you light first?

The host of a game show, offers the guest a choice of three doors. Behind one is a expensive car, but behind the other two are goats.
After you have chosen one door, he reveals one of the other two doors behind which is a goat (he wouldn't reveal a car).

Now he gives you the chance to switch to the other unrevealed door or stay at your initial choice. You will then get what is behind that door.

You cannot hear the goats from behind the doors, or in any way know which door has the prize.

Should you stay, or switch, or doesn't it matter?

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

Only one colour, 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?