An unkown element has been found to occur in two different stable isotopes. One isotope has an abundance of 57.21 percent and has a mass of 120.9 amu. The other isotope has an abundance of 42.79 percent and has a mass of 122.9 amu. What is the average atomic mass of the unknown element?

Which statement describes how phase changes can be diagrammed as a substance is heated? the phase is on the y-axis and the temperature is on the x-axis. the temperature is on the y-axis and the phase is on the x-axis. the time is on the y-axis and the temperature is on the x-axis. the temperature is on the y-axis and the time is on the x-axis.

Which of the following is always a reactant in a combustion reaction? oxygen nitrogen hydrogen carbon

What is the polyatamic ion of thiosulfate