Most chemical reactions can be classified into general categories, such as synthesis, decomposition, single displacement, double displacement, combustion and redox. Classify the following general reactions as to reaction type, and whether the reaction is endothermic or exothermic. 1) element compound -> new element new compound energy 2) compound compound -> new compound new compound energy 3) hydrocarbon oxygen -> carbon dioxide water energy 4) compound energy -> new compound element

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A) the enthralling of formation for pure element in its standard state is always positivehope this : )

The correct answer is "hydrogen".

Ithe undersigned only for use your own email and delete any and copies and of the itself and to be there is a good timewhat does a decrease in temperature indicate about the molecules in a sample of liquid water? decreased chemical energy of the moleculesdecreased kinetic energy of the moleculesincreased chemical energy of the moleculesincreased kinetic energy of the moleculeshow does a sample of helium at 15 â°c compare to a sample of helium at 215 k? the helium at 15 â°c has a higher average kinetic energy than the sample at 215 k.the helium at 15 â°c has lower nuclear energy than the sample at 215 k.the helium at 15 â°c has slower-moving atoms than the sample at 215 k.the helium at 15 â°c has smaller atoms than the sample at 215 k.