Answer:
atoms of isotopes of an element have different numbers of neutrons.
Explanation:
isotopes have the same number of protons, but different numbers of neutrons.
Answer:
The laws are: (1) Every object moves in a straight line unless acted upon by a force.
(2) The acceleration of an object is directly proportional to the net force exerted and inversely proportional to the object's mass.
(3) For every action, there is an equal and opposite reaction.
Answer: 
Explanation: 1 gram is equal to 1000 Milligrams so

Since you go straight across its just multiplication so 0.00200x1000=200mg
To answer it in scientific notation it should just be
mg