Index Fossils Fossils that help with dating are called index fossils.
Index fossils formed from that
• were alive for only a period of geologic time.
• are extinct.
• had hard parts such as shells, bones, and teeth.
• lived across a wide area.

The answer choice is short, relative, geographic, organisms

- lead + phosphoric acid = hydrogen + lead(ii) phosphate

water and alcohols have similar properties because water molecules contain hydroxyl groups that can form hydrogen bonds with other water molecules and with alcohol molecules, and likewise alcohol molecules can form hydrogen bonds with other alcohol molecules as well as with water.