Question

Which procedure involves a physical change in one of the substances?
Responses

building a model rocket propelled by mixing baking soda and vinegar

building a model rocket propelled by mixing baking soda and vinegar

creating salt by reacting sodium metal and chlorine gas

creating salt by reacting sodium metal and chlorine gas

separating a salt solution by evaporating the water

separating a salt solution by evaporating the water

allowing a nail to rust

allowing a nail to rust

Answer 1

Separating a salt solution by evaporating the water.

Evaporation is a physical change (water changes state from liquid to gas but remains H2O); the others produce new substances (chemical changes).