Can anyone tell me a word in the English dictionary which has a silent 'z'?

They came out at night, without being called.
They lost at day, without being stolen.
Who are they?

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

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)?

A man in a car saw a Golden Door, Silver Door and a Bronze Door. What door did he open first?

Replace the letters of words with a number so that the below equation holds true

BASE +
BALL
---------
GAMES
----------

How can one talk without saying a single word?

There are two candles. Both will only burn exactly for an hour. How will you use these two candles to measure forty-five minutes?

A rubber ball keeps on bouncing back to 2/3 of the height from which it is dropped. Can you calculate the fraction of its original height that the ball will bounce after it is dropped and it has bounced four times without any hindrance ?

Two in a corner, one in a room, zero in a house, but one in a shelter. What am I?