Which of the following best describes conditions that scientists hypothesize to have existed on early Earth? Extremely cold temperature
Lack of water vapor in the atmosphere
Presence of self-replicating molecules
Very low levels of free oxygen

Which of the following represents a negatively charged ion? of t 7

Waianapanapa beach in hawaii is a black-sand beach that was formed by waves crashing against volcanic rock. the sand can be very hot on sunny days. which statement best explains why? o a. the black sand has no heat capacity. b. the black sand absorbs no radiation. o c. the black sand is immune to insolation. d. the black sand has a low albedo.

Compare the shapes of the bones of the human skull with the shapes of the bones of the human leg. how do the shapes differ? why are the shapes important?