The physical properties of 10 gram of iron are the same as what property of 20 gram of iron

The answer would be true

Physical properties are characteristic that was not related to the chemical property such as color, density or boiling point. It should be same if the substance is the same. the difference in mass won't change it.
Mass and volume is the example of extensive property, so 10 gram of iron will have different extensive property than 20 gram of iron.

A.(nh4)(2co3)is the correct answer