What kind of reaction is this? C5H8 + 7O2 --> 5CO2 + 4H2O A. Decomposition
B. Combustion
C. Single replacement
D. Combination

B. Combustion .

Explanation:

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In this case, since this reaction is started by pentyne and oxygen which are converted to carbon dioxide and water, we can infer this is a combustion reaction because it involves the burnt of a fuel, in this case the pentyne, by using oxygen in order to yield carbon dioxide and water, which are smaller molecules than the original pentyne.

It is important to notice that these reactions are very exothermic because they go to break the C-H bonds in the fuel which release a considerably high amount of energy.

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chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.