Which particles make up most of the mass of an atom?

Which statement accurately describes the relationship between air pressure, air density, or altitude? as altitude increases, pressure increases. as altitude increases, air density increases. air pressure and density are lowest at sea level. denser air exerts more pressure than less dense air.

This element exists in adundance in the sun. explain how you would go about capturing sunlight. would this captured sunlight contain any of the element?

What is the relation between concentration of reactants and the rate of chemical reaction?