what does the below math rebus puzzle mean?

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

If you were to put a coin into an empty bottle and then insert a cork into the neck, how could you remove the coin without taking out the cork or breaking the bottle?

What number comes next in the series?

5 15 5 18 5 24 14 20 _

In an Art Gallary, When the clock hit 11 am, Artist hung the painting number 30. When it struck 4 pm, he hung painting number 240 and when it struck 7:30 pm, he hung painting number 315.

Can you determine, which painting number will he hang when the time is 9:20 pm?

If you read clockwise, you can form a word by inserting three missing letters in the picture given below. Can you do it?

I can be cracked, made, told, and played. What am I?

Replace the question mark with the correct number, given the pair of numbers exhibits a similar relationship?

? : 3839 :: 11 : 1209

Complete the following series. It.s very logical:

1, 4, 5, 6, 7, 9, 11, __?

Two guards were on duty outside a barracks. One faced up the road to watch for anyone approaching from the North. The other looked down the road to see if anyone approached from the South. Suddenly one of them said to the other, "Why are you smiling?"

How did he know his companion was smiling?