Answer: Rn :)))) no explanation needed
Well, the thing is: we don't really know, as we don't even know how many species there are on earth.
If we take a look at the estimates of <span>World Wide Fund for Nature, an organization that works toward combating species extinction, their estimates vary from 200 to 100 000 - but a probable number is 20 000 (d). </span>
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Answer: n = c / v" "c" is the speed of light in a vacuum, "v" is the speed of light in that substance and "n" is the index of refraction. According to the formula, the index of refraction is the relation between the speed of light in a vacuum and the speed of light in a substance.
Explanation: the relation is the vacuum and the speed of light in a substance.
It could result in it not being good for your joints, as well as in the long run but shouldn't cause problems when your a child. I hope this helps your question!
2.4 meters per second
I hope this helps