Characterize each process as a physical change or a chemical change: (a) making ice cubes; (b) burning natural gas; (c) silver jewelry tarnishing; (d) a pile of snow melting; (e) baking bread.

Physical change -

It refers to any change during any process, where there is no new substance is formed, is referred to as a physical change.

Any change in the state of matter is characterised under physical change.

Chemical change -

It refers to any change in a chemical process, where there is formation of any new substance, is referred to as a chemical change.

From the options given in the question,

The physical change are -

(a) making ice cubes - as there is state change from liquid to solid.

(d) a pile of snow melting - as, there is state change from solid to liquid.

The chemical change are -

(b) burning natural gas - since a chemical reaction takes place, where the natural gas reacts with oxygen.

(c) silver jewelry tarnishing - as chemical reaction takes place.

(e) baking bread - batter is converted to bread, hence there is formation of new substance.