Consider the following properties of the element copper: 

(a) Copper metal cannot be broken down by a chemical change. 

(b) Copper reacts with oxygen in air to give copper oxide. 

(c) Copper, in the form of malachite ore, is found worldwide. 

(d) Copper and tin compose bronze alloy. 

Classify each of the following copper samples as an element, a compound, a homogeneous mixture, or a heterogeneous mixture: 

(a) Copper wire 

(b) Copper oxide 

(c) Malachite ore 

(d) Bronze alloy.