A mixture has unlike parts and a composition that varies from sample to sample. A homogeneous mixture is the same throughout but a heterogeneous mixture has physically distinct parts with different properties. A solution is a homogeneous mixture because it is the same throughout a given sample, but one solution can vary from the next. A solution of sugar in water does not have a fixed, definite composition. An alloy, by the way, is a homogeneous mixture of two or more metals, with the atoms of one metal replacing or occupying interstitial positions between the atoms of the other metal.
Solid ice is melted into liquid water.
A physical change does not alter the identity of matter and involves physical properties only since no new substances are formed. Examples of physical changes include evaporation, condensation, melting, freezing, and dissolving, as well as crushing or bending. When ice melts into liquid water it changes to a different phase of matter but is still recognized as water. The other items are chemical changes, which alters the identity of matter, producing new substances with different properties. An element is a pure substance that cannot be broken down into anything simpler by chemical or physical means.