What does this rebus means ?

PROG WORKRESS

The centre of the third figure is empty. What digit should fit inside?

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?

Find three numbers such that

* When we multiply three numbers, we will get the prime numbers.
* The difference between the second and the first number is equal to the third and second.

What 8 letter word can have a letter taken away and it still makes a word. Take another letter away and it still makes a word. Keep on doing that until you have one letter left. What is the word?

You are given 2 eggs.
You have access to a 100-storey building.
Eggs can be very hard or very fragile means it may break if dropped from the first floor or may not even break if dropped from 100th floor, Both eggs are identical.
You need to figure out the highest floor of a 100-storey building an egg can be dropped without breaking.
Now the question is how many drops you need to make. You are allowed to break 2 eggs in the process

My thunder comes before the lightning; my lightning comes before clouds; my rain dries all the land it touches. What am I?

Where do fish keep their money?

Why do we preferably have round manhole covers and not square ones?

Why is a river so rich ?