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

There were two grandmothers and their two granddaughters.
There were two husbands and their two wives.
There were two fathers and their two daughters.
There were two mothers and their two sons.
There were two maidens and their two mothers.
There were two sisters and their two brothers.
Yet there are only six, who are buried here,
All are born legitimate and relationships clear.
How can this happen?

The doctor prescribed you to take one pill from the bottle every half an hour. The bottle is now left with only three pills.

How long do you think you have before you run out of pills?

What number should come in place of the question mark below?

I am not alive, but I grow; I don't have lungs, but I need air; I don't have a mouth, but water kills me. What am I?

How many times can you subtract the number 5 from 25?

It is a six-letter word.
The first four letters are me.
The second and last letters are the same.
The fourth second and last letter is payment.

Who is it?

On a beautiful Sunday morning, You ordered a hot tea to your hotel room and suddenly you remember an important thing that needed to be done right now will take around 3 minutes to complete.
Like most people you like your tea to be hot while drinking so, when should you pour cream in the tea?
1. straight away
2. Just people, you drink the team
3. Its does not matter

A man and a dog were going down the street. The man rode, yet walked. What was the dog’s name?

Can you figure out the logic I used to decide the order of the following words:
gun, shoe, spree, door, hive, kicks, heaven, gate, line, den