What is the wavelength that has an energy of 4.90x10-19 J ? (Hint: Use algebraic manipulation to solve the energy equation for 2. You will get an answer in meters. Convert it to nanometers (10-m=1 nm).]
Express your answer with the appropriate units.

14 days is the half-life of phosphorus-32

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.