Why is the Hole below a Lock?

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

What does this simple rebus mean?

What part of Turkey has the most feathers?

You measure my life in hours
I serve you by expiring
I vanish faster when I am thin
and slower when I am thick
The wind is my energy
What am I?

There was a competition where the contestants had to hold something. At the end of the event, the winner was a person who had no hands or feet. What was it that the contestants had to hold?

I know a 5-digit number having a property that With a 1 after it, it is three times as large as it would be with a one before it.

Guess the number?

A finger goes in me. You fiddle with me when you're bored. The best man always has me first. What am I?

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

John was working on a Chemical Mixture whose weight comprise 90% liquid and 10% solid. The total weight of the mixture is 20 pounds. After a while, John noticed that some of the liquid evaporated and now the liquid comprises just 50% of the weight.

What is the weight of the chemical mixture now?