To be a useful index fossil, a species must have been rare. true or false

The given statement is False

Index fossils are the fossils that is used as guide or indicator to identify the geologic periods. Index fossils must have a short vertical range and wide geographic distribution and should have evolutionary trends.This fossil need not to be rare to be called as index fossil.

Example: Calico scallop, Scaphites, Inoceramus, Leptodus.

The given statement is False

Index fossils are the fossils that is used as guide or indicator to identify the geologic periods. Index fossils must have a short vertical range and wide geographic distribution and should have evolutionary trends.This fossil need not to be rare to be called as index fossil.

Example: Calico scallop, Scaphites, Inoceramus, Leptodus.

the relative standard reduction potential of the half-cell in which reduction occurs; more positive than the other half-cell. reduction is a chemical process in which electrons are added to an atom or an ion; it always occurs accompanied by oxidation of the reducing agent.