Multiple ChoiceHow many hydrogen atoms and how many oxygen atoms are present in a single molecule of water (H_2O)? (Choose the correct pair of numbers for hydrogen and oxygen atoms, respectively.)41views
Multiple ChoiceAccording to modern science, what was the approximate chemical composition of the solar nebula?25views
Multiple ChoiceA certain atom has 26 protons, 26 electrons, and 30 neutrons. What is its mass number?36views
Multiple ChoiceCalcium has an atomic number of 20 and an atomic mass of 40. Therefore, a neutral calcium atom must have:104views