suppose you find a website that describes the rusting of a nail as a change to only the physical properties of iron. Would that be accurate?

Answer is no

The chemical reaction between iron and oxygen in the presence of moisture or water produces a new substance, which is the rust (iron oxide). In this case, it shows a chemical property.

c. because step up transformer steps up the input voltage i.e increases the input voltage  

the number of turns are greater on the secondary side of step up transformer  

transformer does not handle dc current