Two pieces of the same metal or placed on the table with the piece of metal have the same density mass and texture which characteristic must be the only difference between the two samples A-they contain a different amount of matter per unit volume

B-they have different dimensions

C-they are made up of a different type of matter

D-they have different boiling points

B-they have different dimensions

Explanation:

It was explicitly stated in the question that the both samples are exactly pieces of the same metal. If that is so, pieces of the same metal must have the same density, contain the same quantity of matter, have the same boiling point and have the same amount of matter per unit volume.

However, the two pieces of metal may have different dimensions.

the reaction mixture contains some ammonia, plus a lot of unreacted nitrogen and hydrogen. the mixture is cooled and compressed, causing the ammonia gas to condense into a liquid. the liquefied ammonia is separated and removed. the unreacted nitrogen and hydrogen are then recycled back into the reactor .