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

It is always ahead of me yet I can never see it. What is it?

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?

A plane crashed between the border of Mexico and America. Where do you bury the survivors?

A patient was diagnosed with some ailment. He was given five different tablets to take at night at an interval of 15 minutes.

How long will it take the patient to consume all the five tablets?

I am a ten letters word
The first four letters have the power to rule,
Next, four-letter can be eaten.
The next three-letter represents a lady.
I can fly as well

what am I looking for?

There are 2 cops parked along a one-way street looking for traffic violations. They spot a taxi driver going in the wrong direction, yet they do nothing.

Why?

What is in seasons, seconds, centuries and minutes but not in decades, years or days?

What is so fragile that saying its name breaks it?

What will you call your mother's brother's brother-in-law?