Explain why the synthesized ester does not always match the odour of the fragrance found in nature

10. according to the law of conservation of mass, how does the mass of the products in a chemical reaction compare to the mass of the reactants?

Can someone me with 3 and 4 plz. this is for masteries test.

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