Where was hydrogen discovered

Remember to use the proper number of significant figures and leading zeros in all calculations. gelatin has a density of 1.27 g/cm³. if you have a blob of gelatin dessert that fills a 2.0 liter bottle, what is its mass? 2540 g2500 g3.9 x 10-43.937x 10-4

Sally is making a model of a magnesium atom with an atomic mass number of 24 for her chemistry class. she has foam balls for the protons, neutrons, and electrons. she has added 6 neutrons to her model so far. how many more neutrons does she need to add to complete her neutral atom of magnesium?

When electrolyzing copper (ll) chloride, what reaction takes place at the anode? what reaction takes place at the cathode?