Richter Scale.
Hope this helps!
True is the correct because helio means sun in greek and the sun is in the center of our universe
Cl-35, as the atomic mass of Chlorine (35.45) is closer to the number 35 than to the number 37. A higher abundance of CL-35 isotope would have caused the atomic number (which is an average of the values of all isotopes of a substances taking relative abundance into consideration) to decrease from 36, which would appear to be the average.
The ionic compound is CaSO4
