99 points to the first person who answers
a substance that is made up of all identical atoms is:
a. a chemical
b. an element
c. a compound
d. an alloy

A substance that is made up of all identical atoms is a chemical, specially a chemical compound.

Here are the reasons why the other choices cannot be the

An element would be a single atom and not a substance that consisted of multiple atoms.A compound would be any combination of 2 or more different elements that is held together by chemical bonds, meaning it isn't made up of all identical atomsAn alloy is a substance that consists of more than one element where at least one of them is a metal, meaning it does not have identical atoms.

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~ Padoru

Thermohaline circulation and gyres