Categorize each property as either physical or chemical. Physical Properties
Chemical Properties
melting point
color
density
flammability
corrosiveness
electrical
reactivity with acids
hardness

Physical properties are the properties of a substance that can observed and measured without altering the identity of the substance. Examples of physical properties according to the above question are color, hardness, malleability, electrical conductivity, density, melting point.

Chemical properties on the other hand are the properties of a substance that describes the ability of the substance to undergo chemical reactions based on its composition. Examples include reactivity with acids, flammability.

In other words, to identity a chemical property of a substance we check its ability to be change into a different state via chemical reaction. Rusting of iron is a good example of chemical property.

So therefore, categorizing the properties we have;

Physical properties                                             Chemical Properties

Melting point                                                                Flammability

Color                                                                        Reactivity with acids

Density                                                                       Corrosiveness

Electrical conductivity

Hardness

the answer is c. nacl