Answer:
Fossil record gives evidence of evolution: Earliest land animals. A fossil called Tiktaalik has been found to be halfway between a fish and the earliest land animals
Explanation:
Fossil record documents the hystory life by fossils that have been found in the sedimentary rock layers
The fossil record matches the geologic record:
The oldest forms of life were much more simple than the newest forms of life.
Explanation:
The geologic record can be associated with sedimentary datable layers
DONE
You can use A.D for before his birth and B.C. for after.
Answer:
Starting molecules not completely and quickly convert to its possible product because an activation energy barrier exist that must be overcome for conversion to product.
Explanation:
The activation energy of a chemical reaction is closely related to its rate. This is because molecules can only complete the reaction once they have reached the top of the activation energy barrier. The higher the barrier is, the fewer molecules that will have enough energy to make it over at any given moment.
Many reactions have such high activation energies that they basically don't proceed at all without an input of energy. For instance, the combustion of a fuel like propane releases energy, but the rate of reaction is effectively zero at room temperature. Once a spark has provided enough energy to get some molecules over the activation energy barrier, those molecules complete the reaction, releasing energy. The released energy helps other fuel molecules get over the energy barrier as well, leading to a chain reaction.
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Answer:
The best explanation was provided by the student Tara who said: "Through photosynthesis, the CO2 and water are changed into new substance, glucose, therefore it is considered a chemical change".
Explanation:
A chemical change is one which is not easily reversible and which results in the formation of new subsatances.
For example, in photosynthesis,a new substance, glucose is formed from the original substansubstances, carbon dioxide and water. Also, the reverse process of the formation of carbon dioxide and water from glucose is not easily obtained in plants.
From explanations provided by the students :
Luke does not give any explanation of the process but only an observation
Jackie's explanation does not state the main reason why a chemical change differs from a physical one.
Tara, gives the best explanation as the reason why a change that occcured is a chemical change is clearly stated.
Skyler does not state the main reason why photosynthesismis a chemical change as well, because even physical changes like evaporation of water involves solar energy.
