What is the decimal at the bottom of an element on the periodic table?

Atomic mass

Step-by-step explanation:

That number is the atomic mass of the element. It is also the same numerical value as the molar mass, which is the mass of 1 mole of the element.

So, in this case, sodium (Na) has an atomic mass of 22.99 atomic mass units (amu).

Hope this helps!

4th option is correct xy=-10

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