What does below chemistry rebus means?

There is something which you can be arrested for attempting but not for successfully completing.

There are 20 people in an empty, square room. Each person has full sight of the entire room and everyone in it without turning his head or body, or moving in any way (other than the eyes). Where can you place an apple so that all but one person can see it?

Take away the whole and some still remain. What is it?

John, Jack and Jill are in a desert. John doesn't like Jill and hence decides to murder him. He poisons the water supply of Jill. Since it is a desert area, Jill must drink or he will die of thirst.

Jack does not know of the actions of John and also decides to murder Jill. To succeed in his ill motives, he removes the water supply of Jill so he dies of thirst.

Jill dies due to thirst. Who murdered Jill?

Can you count the number of squares in the given picture?

The answer I give is yes, but what I mean is no. What was the question?

In the city of Brain Teasers, 5% of people do not list their phone numbers. Now if we select random 100 people from the phone directory, then how many people selected will have unlisted phone numbers?

What can you deduce from the following BrainBat?

CRY
LMKI

Can you find out what is missing?

1 3 5
2 4 ?

Hint: It's not six. Think out of the box.