What can you catch but never throw?

How many triangles can you find in this given picture?

Why are all black people so quick ?

What always comes into a house through the keyhole?

Can you find a five letter word that is left with only two letters if one is removed?

What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

I am the one who remains awake when you sleep. But I need to rest when you awake. Who Am I?

Let's play a word game. Following are some meaningless words that can be completed by adding random letters on either side of the word.

For example, the word "rdo" can be formed into "pardon".

Using the same technique, can you complete the given words?
ecalc
airb
rinci
tibac
uidel
gorit
igna
eyho

If it took eight men ten hours to build a wall, how long would it take four men to build it?

Using the clues below, what four numbers am I thinking of?

The sum of all the numbers is 31.
One number is odd.
The highest number minus the lowest number is 7.
If you subtract the middle two numbers, it equals two.
There are no duplicate numbers.