How many grams of calcium hydride are needed to form 4.550 g of hydrogen gas

What is the number of moles of chemical units represented by 9.03x10^24? and how do i show work? (dumb it down )

If 22.5 liters of oxygen reacted with excess of hydrogen, how many liters of water vapor could be produced?

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