Which set of procedures and observations indicates a chemical change?

A) Ethanol is added to an empty beaker and the ethanol eventually disappears.

B) A solid is gently heated in a crucible and the solid slowly turns to liquid.

C) Large crystals are crushed with a mortar and pestle and become powder.

D) A cool, shiny metal is added to water in a beaker and rapid bubbling occurs.

Solution:

the answer is D because the beaker water is being affected in some measure by the addition of the cool shiny metal - there is no mention of other heat being applied.

this is required solution.

The correct answer is D. A cool, shiny metal is added to water in a beaker and rapid bubbling occurs.

Explanation:

In chemistry, the matter can undergo two main changes: physical change and chemical change. A physical change occurs as there is a change in the state but not the properties, for example, a solid becomes a liquid or a liquid becomes a gas. On the other hand, a chemical change involves a change in composition; this can be identified due to the formation of bubbles or major changes such as a difference in color or odor. According to this, the option that indicates a chemical change is "A cool, shiny metal is added to water in a beaker and rapid bubbling occurs" because in this case there is a formation of bubbles that indicates the composition of the substances has change and therefore a chemical change occurred.