Number 4 i don't understand it's science

Which two particles are found in the center of an atom

What is the weight of a feather (mass = 0.0001 kg) that floats through earth's and the moon's atmospheres?

Select all the correct answers. which changes will increase the rate of reaction during combustion? decreasing the area of contact between the reactants adding more oxygen to the reaction removing heat from the reaction changing the reactants from solid form to powdered form lowering the exposure of the reactants to air