They saw how smoking effected the body since smoking was pushed as something good for a long time, a lot of people started smoking and after a few years doctors finally saw a difference between a smokers body and a non smokers body
To make ATP, cells must join together ADP & a phosphate using energy from food. A phosphate is removed from an ATP molecule in order to provide energy for the cell. Thus, the ATP molecule turns into an ADP molecule. We eat food which gives us energy to add another phosphate group to the ADP molecule, turning it into an ATP molecule. The cycle then begins again.
Answer: The correct answer is black because the product of its side and mass is lower.
Explanation: Density of a substance is defined as the mount of matter that can be stored in a given volume.
Mathematically,

As, density is inversely proportional to the volume of the substance.
The substance will be more denser if it has less volume and it will be less denser if the volume is more.
We are given two cubes having different sides.
Volume of the cube is calculated by using the formula:

where, a = side of the cube.
Black: The side of this cube is 2 and volume will be =
Yellow: The side of this cube is 3 and volume will be =
As, the volume of black cube is less. So, this cube will be more denser.
Density of black cube: 
Density of Yellow Cube: 
Hence, black cube will be more denser because the product of its side and mass is lower.
Answer:
(1) a table tennis ball
Explanation:
The earth will most closely resemble any type of sphere or circular ball.