Answer:

Explanation:
Hello,
In this case, the enthalpy of combustion is understood as the energy released when one mole of fuel, in this case octene, is burned in the presence of oxygen and is computed with the enthalpies of formation of the fuel, carbon dioxide and water as shown below (oxygen is circumvented as it is a pure element):

Thus, since we already know the enthalpy of combustion of the fuel, for carbon and water we have -393.5 and -241.8 kJ/mol respectively, thereby, the enthalpy of combustion turns out:

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Answer: C the study of living things
Explanation:
Answer: It is important for an equation to be balanced because if it is not then the reactants won't match the products.
Explanation: I don't know if you will understand this but here:
Let's say you're cooking eggs, you're reactants so to speak would be 3 eggs and 1 tablespoon of oil so you put it together using heat and a pan. Your products have to match what you have in the beginning. You cannot have an equation that looks like this
Reactants = 3eggs + 1Tbsp oil ---pan/heat---> 6eggs + 1 cup of oil
You cannot get something from what you don't have. The number of how much of an element you have must be the same of both sides of the equation.
The classification of living things makes it easier for scientists to answer many important questions.
Examples:
-How many known species are there?
-What are the defining characteristics of each species?
-What are the relationships between these species?