Scientists used to believe that chemical reactions fueled the sun. Why did this lead them to believe that the sun was very young? Please explain in at least 2 sentences. Will give brainliest.

An animal cell loses the ability to convert energy stored in food to energy that the cell can use. which of the cell's organelles has stopped working? a.the mitochondria b.the nucleus c.the vacuoles d.the endoplasmic reticulum

What type of matter is made of only one kind of atom

How many valence electrons are in atom of radon?