Answer
(a) compound
(b) homogeneous mixture
(c) homogeneous mixture
(d) element
Work Step by Step
(a) compound
Water is a compound because it is made up of two elements (hydrogen and oxygen) chemically combined in defined ratios to form a new substance.
(b) homogeneous mixture
Window cleaner is a homogeneous mixture because it is made of different substances but is uniform and consistent throughout.
(c) homogeneous mixture
14-karat gold is a homogeneous mixture because it is an alloy made up of gold and other metals such as copper, and its component metals are mixed together in a consistent fashion.
(d) element
Copper is an element because it cannot be broken down any further into any constituent parts that can still be identified as copper. On the periodic table, copper is element 29 with the elemental symbol Cu.