Question

lesson 42 - classification of materials
the spoiling of milk is an example of which type of change?
(1 point)
neither
both
chemical
physical

Explanation:

When milk spoils, bacteria convert lactose into lactic acid. This is a chemical reaction as new substances (lactic acid) are formed, and it's not reversible by simple physical means like filtration or evaporation. Physical changes (e.g., melting ice) don't create new substances. Since a new substance (lactic acid) is formed here, it's a chemical change, not a physical one, and clearly not "neither" or "both" (as it's only chemical).

Answer:

chemical