What happens to the pH of the solution as you add more substance to it?

If it's a buffer solution, the pH remains unchanged.

If it's a normal solution, and an acidic substance is added to it, the pH lowers.

If a basic substance is added to it, the pH increases.

radioactive decay occurs in unstable atomic nuclei – that is, ones that don't have enough binding energy to hold

the nucleus together due to an excess of either protons or neutrons.

a  solution  is always transparent, light passes through with no scattering from solute particles which are molecule in size. the  solution  is homogeneous and does not settle out. a colloid is intermediate between asolution  and a  suspension. while asuspension  will separate out a colloid will not.