Answer: c.They have a unique set of properties that can be used as identifiers.
Explanation:
Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.
Compounds can be decomposed into simpler constituents using chemical reactions.
Example: Water
Compounds have different properties than the elements it is made up of.
Thus the most accurate description of compounds is that they have a unique set of properties that can be used as identifiers.
Place a burning splint near the opening of a test tube. If a popping noise occurs, it's probably hydrogen. Place a glowing splint in the test tube, and if it reignites, it could be oxygen. Place a burning splint into a test tube, and if it goes out, it could be carbon dioxide.
1 is correct, i’m not sure if that’s the answer your looking for because of the wording, but if it’s a multiple choice answer then that’s it