Which substance can't be broken down by chemical means? (1) ammonia (2) antimony (3) methane (4) water

Antimony cannot be broken down by chemical means because it is an element, a principle building block of matter. All other choices are compounds, which can be separated if put through enough stress to break the bonds between the atoms.

4- c, because all matter stays the same no matter what. it is still there. 5- b, because matter is known as mass. 6-c because, flammability is a chemical property. malleability is changing the shape of an object.

257 grams h2o i think