Answer:
The atom
Explanation:
The basic unit of matter is the "atom." All matter consists of millions of atoms that within the atom contains electrons, protons, and neutrons. Knowing how many electrons, protons, and neutrons a atom has can determine the element which are substances that are on the periodic table.
Hope this helps.
It is use by Eye Care Professionals To check the eyesight of a person.
If u would have visited a eye care centre u would have noticed a chart like this--
If a person can see all the letters from a distance his eyesight is Perfect.If that person misses a letter or a line from the grid eye treatment or spectacles are given to the person for improving their eyesight

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Explanation:
- About 14 percent were current or recent problem drinkers, or nearly 33 million nationally, and 30 percent
<h2>hope it helps</h2>
Depression and anxiety. or at least thats what it is for me.