What is so fragile that saying its name breaks it?

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

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

What famous saying does this rebus mean?

COME SERVED <---
COME SERVED
COME SERVED
COME SERVED
COME SERVED

There are five vowels (a, e, i, o, u) in the English language.
Can you tell us a word that contains all these vowels?

By using 'because' continuously three times, can you make an English statement ?

Four men were in a boat on the lake. The boat turns over, and all four men sink to the bottom of the lake, yet not a single man got wet! Why?

While handling a project, the landscaper is asked by the owner of the mansion that he wants four trees in front of his mansion that are exactly equidistant from each other.

How will he do it?

Find the number of squares in the below-given picture.

A man lives on the fifteenth floor of an apartment building. Every morning he takes the elevator down to the lobby and leaves the building. In the evening, he gets into the elevator, and, if there is someone else in the elevator, or if it was raining that day, he goes back to his floor directly. Otherwise, he goes to the tenth floor and walks up five flights of stairs to his apartment. Can you explain why he does this?