The oldest rocks found on the earth's surface date back about billion years.

Which of the following represents an upside-down image?

Avalue that describes how heavy an object is and is related to the force of gravity is

Which is the best predictor of the radioactive nature of an isotope? o the proton-to-electron ratio the neutron-to-proton ratio o the neutron-to-electron ratio the electron-to-proton ratio