What is an element?

A.

a material that is shiny and usually hard and strong

B.

a substance made of just one kind of atom that cannot be broken down into something simpler

C.

a substance made up of hydrogen and one other kind of atom

D.

a substance made of just one kind of molecule that cannot be broken down into something simpler

B) a substance made of just one kind of atom that cannot be broken down into something simpler

Explanation:

Elements are what you find on the periodic table of elements.

Take oxygen, for example. You can have one or multiple atoms, but if they are all oxygen atoms it's an element.

in chemistry, a solution’s concentration is how much of a dissolvable substance, known as a solute, is mixed with another substance, called the solvent. the standard formula is c = m/v, where c is the concentration, m is the mass of the solute dissolved, and v is the total volume

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