Which of these choices is an example of a physical property?

a) the combustion of gasoline in a car engine

b) the effect of acid rain on automobiles

c) the tarnishing of silverware

d) the texture of a piece of chocolate

i cannot decide between c and d.

I'm not massively impressed by the premise of the question, I really hope this kind of thing never came up in an exam because it is a little vague. However given this is chemistry, one answer does shout at me above the others.

A is a chemical reaction fundamentally, following an equation of the type:

Fuel + oxygen --> water + carbon dioxide

B is also a chemical reaction. This time the acid, to my understanding, actually acts as a catalyst in the rusting of iron as opposed to being a reactant, but still it is fundamentally chemical.

C is also a chemical reaction, as the silver reacts with oxygen and other gases in the air to form black silver oxide and other dull compounds.

This leaves D, the correct answer. Texture is a very complex thing. It regards how stuff is held together, what is in something, how it was made. It's very physical really.

I hope this helps you :)

The mass has escaped into a gas which you can not see so the law stays true.