What is the relationship between the weight of a pencil and the normal force of a pencil?

Equal and opposite

Explanation:

According to third law of motion,

"Every action has an equal but opposite reaction."

So weight of a pencil is acting downwards on any horizontal surface, while the normal force acting will always be upward. Please note that it is assumed when the pencil must be at rest. Because, at the rest, sum of all forces must be "zero", so

If weight of pencil is "W", then normal force "N" must be equal to "W" but in opposite direction.

So, sum of forces

∑F = W + (-W)

∑F = 0

a chemical reaction happens

explanation:

< > according to newton's third law of motion, forces always act in equal but opposite pairs. another way of saying this is for every action, there is an equal but opposite reaction.< >