A newly discovered element, Y, has two naturally occurring isotopes. 87.8 percent of the sample is an isotope with a mass of 267.8 u, and 12.2 percent of the sample is an isotope with a mass of 269.9 u. What is the weighted average atomic mass for this element?

267.9 u

268.1 u

268.9 u

269.1 u

Question

A newly discovered element, Y, has two naturally occurring isotopes. 87.8 percent of the sample is an isotope with a mass of 267.8 u, and 12.2 percent of the sample is an isotope with a mass of 269.9 u. What is the weighted average atomic mass for this element?

 267.9 u

 268.1 u

 268.9 u

 269.1 u

jfraser · Answer

find 87.8% of 267.8u, and find 12.2% of 269.9u. Add together.