The half-life of strontium-90 is 28 years. how long will it take a 52 mg sample to decay to a mass of 13 mg?

What is the ph of a solution that has a hydrogen ion concentration of 1.0 * 10 -9 m?

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

What is the mass of phosphorous in a 51-kg person