This chemical reaction can also be written as
2C2H6+7O2-->4CO2+6H2O
This is a chemical reaction because reactants are converted into products. This is the combustion of ethane where ethane and oxygen have been converted into carbon dioxide and water
It is the crust, the least dense layer.
Lions walk on 4 legs, humans walk on 2. female lions live in groups but are taken over by groups of male lions from time to time, human adults tend to live alone or in pairs with their offspring. Humans can talk and lions cannot. lions have manes around the face.
A chemical change is characterized of the formation of new substances or a chemical reaction. There are a number of observations that we can see if this type of change happens. One would be the formation of gas bubbles, this indicates that one of the products is a gas. Another observation would be a formation of a precipitate in the solution, it would indicate that the new solid formed is not soluble in the solution. A permanent color change in the solution would also indicate a chemical change because it may be that the new substance that is formed has its own distinct color when in solution.