The two are potassium and rubidium. Why? Na is an alkali metal. As you go down the metals become more reactive.
Calcium has 20 protons. Why? The atomic # is 20 (the one at the top).
It has 20 neutrons. Why? The atomic mass (the number on the bottom) is ~40, ignoring electron mass. 40- 20 protons = 20 neutrons.
It has 20 electrons.
Why? The # of protons and electrons is the same. Ions aren't on the periodic table.
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Amniotic Egg - This type of egg does not require water. Organisms could lay their eggs on land they would not dehydrate.
Lungs - got to be able to extract oxygen from their environment for cellular respiration.<span />
Answer:
Blood cells are a lot smaller than nerve cells and have a disc-shaped structure, both great traits for moving quickly through small spaces. Their disc shape also provides them with a big surface where lots of oxygen can enter the cell.
hope it helps
True, GPS Uses Latitude,Longitude,Elevation(x,y,z) To Locate<span />
troposphere, troposphere is where all the weather comes from
