An atom having 52 protons and 54 electrons would have an atomic number of 52 and a net charge of -2. This element would be 52 Te 2-, or choice A.
C, it prevents the Earth from ultraviolet radiation and other harmful substances from space
It is really easy if you look up an electron configuration table (one that looks like a periodic table) and then just go down the rows left to right, top to bottom, and just stop when you get to where the element is on the table.