Question

a student was studying physical and chemical changes. the student carried out some procedures in the laboratory and recorded observations. for one of the procedures, the student concluded that a physical change took place, but not a chemical change. which of the following could have been the results of the procedure? a a cube of metal was changed into a flat sheet of metal. b when two liquids at room temperature were combined in a beaker, the beaker became hot. c when two clear liquids were combined, the resulting mixture was cloudy. d when a colorless liquid was added to a blue liquid, the resulting solution was yellow.

Explanation:

• Option A: Changing a cube of metal into a flat sheet of metal is a physical change. It only changes the shape of the metal, and no new substances are formed.
• Option B: When two liquids at room temperature are combined and the beaker becomes hot, it indicates a chemical reaction (exothermic reaction where heat is released as a new substance is formed in most cases).
• Option C: When two clear liquids are combined and the resulting mixture is cloudy, it usually means a precipitate (a new solid substance) is formed, which is a sign of a chemical change.
• Option D: When a colorless liquid is added to a blue liquid and the resulting solution is yellow, it likely means a chemical reaction has occurred (a new colored substance is formed).

Answer:

A. A cube of metal was changed into a flat sheet of metal.