What does below chemistry rebus means?

A woman lives in a skyscraper thirty-six floors high and is served by several elevators which stop at each floor going up and down. Each morning she leaves her apartment and goes to one of the elevators. Whichever one she takes is three times more likely to be going up than down. Why?

How many times can you subtract the number two from the number fifty?

I am lying and I always lie. Tell me whether I am lying or telling the truth.

Below is the sum of symbols in each row and column in the figure. Analyzing the figure, can you find out the value of the symbols?

Identify Me

Hint1: I am a god
Hint 2: I am a planet
Hint 3: measurer of heat

While preparing the table for dinner, wife came up with an idea to tease his mathematician husband. She asked her husband to pick nine toothpicks and make ten without breaking any toothpick.

The husband was also smart and did it within seconds. How ?

Count the number of triangles in the picture below:

The teacher told the student that if he told a lie then he will be expelled from school and if he told the truth then he still is expelled from school.

What can a student say to prevent his being expelled from school?

How many bananas can you eat if your stomach is empty?