Anewly discovered element, z, has two naturally occurring isotopes. 90.3 percent of the sample is an isotope with a mass of 267.8 u, and 9.7 percent of the sample is an isotope with a mass of 270.9 u. what is the weighted average atomic mass for this element?

atomic mass=percentage of isotope a * mass of  isotope a + percentage of isotope b * mass of  isotope b+...+percentage of isotope n * mass of isotope n.

Data:
mass of isotope₁=267.8 u
percentage of isotope₁=90.3%

mass of isotope₂=270.9 u
percentage of isotope₂=9.7%

Therefore:

atomic mass=(0.903)(267.8 u)+(0.097)(270.9 u)=
=241.8234 u + 26.2773 u≈268.1 u

the mass atomic of this element would be 268.1 u

"electrical energy" transforms to "thermal energy".hope my answer has you : )

Ibelieve the answer is weathering,hope my answer has you : )