Need answer asap when starting a car some energy is used to increase the fuel’s temperature during ignition. this energy causing combustion is 1). absorbed energy 2). chemical energy 3). activation energy 4). latent energy in order for a combustion reaction to occur, like the burning of fossil fuels, what element is required? 1). sulfur 2). hydrogen 3). oxygen 4). helium which of the following is a chemical reaction? 1). crushing pepper 2). rotting vegetables 3). chopping vegetables 4). dew formation if a synthesis (also called combination) reaction is the formation of 1 product, what is the opposite reaction type? 1). combustion 2). replacement 3). neutralization 4). decomposition