What must an element be in order to
replace another element in a compound?

In an ionic compound, an element must be able to lose or gain electrons with another element in order to obey the octet rule.

Ifound this on google “according to the findings, a foramen magnum positioned toward the base of the skull is found not only in humans, but in other habitually bipedal mammals as well.” i hope this you for what your looking for

They both determine the exact age of rocks.