Radioactive elements comprise a majority of the "ACTINIDES"
These are elements in the bottom row of the periodic table.
Amino acid itself a Monomer of Protein
Hope this helps!
Maria and craters are explained below:
<u>Explanation:
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- The Moon is divided into light area lunar highlands and a dark area called Lunar Maria.
- Lunar Maria is large, dark, basaltic plains formed on earth's moon formed by ancient volcanic eruptions.
- Craters are formed when an impacting object falls and hits the moon's surface with greater speed and also formed as a result of the outward explosion of rocks.
- Craters are often caused by asteroids and meteorites with the lunar surface.
- Unlike earth-moon does not have an atmosphere to protect itself from impacting bodies. This is the reason for more number of craters formed on earth.