I need help with this answer

What did the first language sound like

In general, characteristics that an organism survive and reproduce become more common over time. what mechanism of evolution causes this?

You are working in the lab and are working with the same element but with varying isotopes of the element. you are working with c-11, c-13, c-14, and c-15. what is the average atomic mass of this element? (use periodic table) a- 12 b-15 c-14 d-13