Can you replace the question mark with the correct number?

It's a 7-letter word.
If we remove 1 letter from it, it remains the same.
If we remove 2 letters from it, it remains the same.
If we remove 3 letters from it, it remains the same.
If we remove all the letters from it, still it remains the same.
What is it?

The doctor advised his patient to take a tablet after every fifteen minutes. He gave him five tablets in total.

How much time will he take to have all the five tablets?

What came first, the chicken or the egg?

There was a strange boy who was born before his father. How can this be possible?

Pooja gave Neha as many Ponds as Neha started with.
Neha then gave Pooja back as much as Pooja had left.
Pooja then gave Neha as back as many Ponds as Neha had left, which left Pooja broke and gave Neha a total of 80 pounds. How much did Pooja and Neha have at the beginning of their exchange?

Can you find the missing piece of the Porsche?

There are three Athletes (John, Tarun and Harish) and their individual Coaches (Jacob, Meenaxi and Priyanka) standing on the shore.
No Coach trusts their Athlete to be near any other Coach unless they are also with them.
There is a boat that can hold a maximum of two persons.
How can the six people get across the river?

I am a number I am not an odd number I am higher than 90 I am not higher than 100 If you subtract me from 100, you get nothing. What number am I?

A man wants to cross the pit of fire which is 25 feet in length and he has 2 planks(fire resistant) 19 feet in length. How can he cross the pit of fire alive?