An atom has a mass number of 19 and an atomic number of 9. What element is it? What is its symbol? How many protons, neutrons, and
electrons does it have?

When the following equation is balanced using the smallest possible integers, what is the coefficent of oxygen gas? c7h16o(g) + o2(g) → co2(g) + h2o(g) -1 -5 -8 -16 -21

Which other elements contain the same number of outer electrons as sodium

According to each substances heat of fusion, which of the items below requires more heat to be added per gram of substance to go from solid to liquid? silver sulfur water lead