What does does this rebus picture means ?

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

John’s parents have three sons: Snap, Crackle, and what’s the name of the third son?

I have two sand hourglasses:
1. A 7 minute one and
2. An 11-minute one.

Using just these 2 sand hourglasses, how can I measure time as 15 minutes?

I organized a small get together at my home.
In the party , i have a barrel with some whiskey in it.

Suddenly Guest 1 say 'I bet this barrel of whiskey is more than half full'.
'No, it's less than half full' Guest 2 replied.

I don't have any measuring instrument and without removing whiskey from it , how can i determine which of the guest is right ?

Different lights make me strange by changing me into different sizes. What am I?

What has a bottom at the top?

A new Engineering building containing 100 offices had just been completed. John was hired to paint the numbers 1 to 100 on the doors. How many times will John have to paint the number nine (9)?

Can you count the number of triangles in the given picture?

Who can jump higher than a Mountain?