Question

A student takes four samples of a white crystalline solid and places each in a well plate. On top of each sample, she carefully places 20 drops of clear mystery liquids A, B, C and D. Her results for each well are: Liquid A: The solid dissolves quickly. Liquid B: The solid appears unchanged. Liquid C: The solid floats on top of the liquid. Liquid D: Fizzing occurs and the solid disappears. Which combination of solid plus liquid indicates a chemical change has taken place?

Answer 1

Dissolving doe not indicate or guarantee a chemical change.  Most of the time it is a physical change.

Unchanged solid in a liquid does not even indicate any change.

Solid floating on top of liquid does not indicate any change, physical or chemical.

When a mixture creates a new compound (gas from mixing solid and liquid), there is a chemical change.

Answer 2

Answer:

The administration of liquid D shows a chemical change taking place.

Explanation:

A chemical reaction or a chemical change refers to a procedure where one or more components get changed into one or more novel and distinct substances. It can be said that a chemical change refers to a chemical reaction in which the realignment of atoms takes place.  

A physical change can get reversed, while a chemical change generally cannot get reversed. When a chemical change takes place, there is also a variation in the system's energy. A chemical change, which emits heat is known as an exothermic reaction, and the one that captivates heat is known as an endothermic reaction.  

When the liquid D is placed over the white crystalline solid, fizzing took place and the solid got disappeared. Thus, the solid form got transformed into a new substance with a fizzing sound showing the emergence of heat, all this indicates a chemical change taking place.