What is the atomic number for an element whose mass number is 78 and contains 47 neutrons?

What are the percent by mass of copper in penny lab

Harvey mixes two liquids. which observation of the new mixture most likely indicates a precipitate is forming?

Consider the following reactions. (note: (s) = solid, (l) = liquid, and (g) = gas.) mg(s) + ½o2(g) → mgo(s) + 146 kcal/mole h2(g) + ½o2(g) → h2o(g), δh = -57.82 kcal/mole what type of reaction is represented by the previous two examples?