What does below chemistry rebus means?

Find The Next Number in this series.
1, 2, 6, 42, 1806 ?

A few friends are enjoying their sea voyage in a boat full of apples. On the way, they felt hungry and thus decided to eat the apples. Together, they ate two dozen of apples. When they have eaten the apples, will there be any change in the water level?

What can run but never walk, have a mouth that never speaks, have a head that never weeps, and have a bed but never sleeps?

Four children having five rocks each were playing a game in which they had to throw the rock at a particular solid area in the water. Child 1- Succeeded in throwing three rocks at a solid area but one of the rocks sunk. Child 3 - His aim was so bad that all rocks got sunk. Child 4- He was awesome and none of the rocks got sunk. Child 2 - Was the winner but was struck by a rock in the head and died. Who killed Child 2?

The chance of Mr John winning the lottery is 10%. All participants lined up and Mr John is 4th in the row. The first three participants lose the lottery.

What is the chance of Mr John now?

Can you calculate the probability of getting a sum of six when a dice is thrown twice?

Three logicians went to bar for having a drink. The bar person asks the logicians "Do they all want to have the drink?". The first logician replied, " I don't know". The second logician replied, " I don't know". What is the reply of the last logician?

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?

If in a car race, the man who came two places in front of the last man finished one ahead of the man who came fifth, how many contestants were there?