Question

which of the following represents an element? caco₃ h₂o nacl h₂

Explanation:

An element is a pure substance that cannot be broken down into simpler substances. $CaCO_3$ (calcium carbonate) is a compound made of calcium, carbon, and oxygen. $H_2O$ (water) is a compound made of hydrogen and oxygen. $NaCl$ (sodium chloride) is a compound made of sodium and chlorine. $H_2$ (hydrogen gas) is an element as it consists of only hydrogen atoms.

Answer:

$H_2$