Which of the following is an example of a physical change ? a. a piece of iron being heated until it melts b. silver jewelry tarnishing c. a piece of wood burning

answer: you could do some invislibe ink.

explanation: i will tell you how to if u answer my question.

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.