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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Answer:
1. Use less cars travel way less with them if youan use a bike or walk to try stop too much CO2 being produced
2. Use less papaer or recyle trees are being cut down for them wich break down habittats and prevents filtrating CO2
3.RECYLE recylimg is something everyone can do it helps stop polution, rubish being frown in the seas oceans and animals eating them
Since carotenoids stabilize dangerous free radicals, we can assume that their function is to protect the cell from the free radicals.