The ratio of parent to daughter atoms after two half-lives is therefore 1:3 (one-quarter to three-quarters).
Which of Earth's layers is comprised mainly of extremely hot liquid metals?
A. Crust
B. Mantle
C. Outer Core
D. Inner Core
Answer: C outer core.
Explanation:
Outer core is a liquid mix of iron and nickel.
Answer:
single-celled micro-organisms
Explanation:
The first living things on Earth, single-celled micro-organisms or microbes lacking a cell nucleus or cell membrane known as prokaryotes, seem to have first appeared on Earth almost four billion years ago, just a few hundred million years after the formation of the Earth itself.