Answer:
Atoms are single neutral particles.
example: Ne, O
Molecules are neutral particles made of two or more atoms bonded together.
example:O2,HCl
Answer:
Net force on the block is 32 N.
Acceleration of the object is 6.4 m/s².
Explanation:
Let the acceleration of the object be
m/s².
Given:
Mass of the block is, 
Force of pull is, 
Frictional force on the block is, 
The free body diagram of the object is shown below.
From the figure, the net force in the forward direction is given as:

Now, from Newton's second law of motion, net force is equal to the product of mass and acceleration. So,

Therefore, the acceleration of the object in the forward direction is 6.4 m/s².
Your weight pushing down on the chair is the action force. The reaction force is the force exerted by the chair that pushes up on your body.
How many seconds did the wildebeest run??