Question

Properties of substances can be classified as physical or chemical properties. Which statements describe chemical properties? (Choose all that apply)
A. A magnet is attracted to a piece of metal.
B. A wire sags when weight is attached to it.
C. Silver tarnishes and becomes black when exposed to oxygen.
D. Water heated over a flame begins to bubble and evaporate.
E. Diesel fuel burns when it is heated

Answer 1

The correct answers are options C, that is, silver tarnishes and becomes black when exposed to oxygen, and option E, that is, diesel fuel burns when it is heated.  

Chemical changes refer to the modifications in which the chemistry at molecular level is modified as the initial substance gets transformed into a new and different final substance. This change occurs with the dissociation of old bond and production of new bonds respectively.  

Silver gets tarnished and becomes black when exposed to oxygen. This refers to a chemical change as silver a white and lustrous substance gets transformed into a tarnish black final substance. However, silver does not easily react with oxygen at usual circumstances. It easily reacts with sulfur comprising components in the air and generates black compound as Ag₂S.  

Burning of diesel fuel when it is heated. Diesel refers to a mixture of hydrocarbons varying approximately from C₁₀H₂₀ to C₁₅H₂₈. When these hydrocarbons get burnt they generate novel substances, that is, carbon dioxide and water. Hence, it is also a chemical reaction.