How is a PH investigation different from a controlled experiment

Which type of orbits are found in the principal energy level n = 2 a - s b - s, f c - s, d d - s, p e - s, p, d

Between 2014 and 2016, more than 25,000 children in flint, michigan, drank water that was contaminated with lead from lead pipes. during this time, the city claimed the water was safe to drink. which of these actions could the city have taken to ensure that the drinking water was free from lead?

Type the letter that represents the correct location for each particle type below.