A penny having a mass of 2.5559 g was dissolved in 20 mL of 8 M HNO3. The resulting solution was transferred to a 100.00-mL volumetric flask and diluted to the mark with water. This solution was found to have a concentration of 1.06 x 10-2 M Cu2 . What is the % by mass of copper in the penny

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

Consider hydrogen in an excited state n = 5n=5 that emits photons to reach the ground state. there are various possible transitions other than straight to the ground state that can occur; for example, it can drop to the n = 3n=3 state followed by the n = 3n=3 to the ground state transition. which of the possible transitions will result in the emission of a photon in the visible region?

Organisms are classified as producer or consumers according to the way they ?