Question

1. a student mixed two liquids in a flask during science class. which of the following observations does not necessarily indicate that a chemical change has taken place? a. a color - change from dark green to light green b. production of a white solid at the bottom of the flask c. the formation of a new substance d. the flask becoming warm to the touch without adding heat

Explanation:

A color change can sometimes be a physical change (like dilution - related color change). A flask becoming warm without adding heat can be due to an exothermic physical process like dissolving some salts. But the formation of a new substance is a clear - cut sign of a chemical change. Chemical changes involve the breaking and forming of chemical bonds to create new substances with different chemical properties.

Answer:

C. The formation of a new substance