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

superhelp101 · Answer

when i worked this out I got the answer to be the second one. Is that right? @DW101796

anonymous · Answer

0.122 * 269.9 + 0.878 * 267.8 = 268.1 


Correct!

superhelp101 · Answer

yeah!