I need help please is for today ):

Which of the following is always a reactant in a combustion reaction? oxygen nitrogen hydrogen carbon

An atom of which element reacts with an atom of hydrogen to form a bond with the greatest degree of polarity ?

Let the ed50 of a recreational drug be defined as the amount required for 50% of a test group to feel high or get a buzz. if the ed50 value of ethanol is 470 mg/kg body mass, what dose would a 70 kg party goer need to quickly consume in order to have a 50% chance of getting a buzz? 235 mg 470 mg 32,900 mg 35,000,000 mg