<span>If thermal energy (heat) must be added to a chemical reaction in order for the reaction to take place, the reaction is endothermic. </span>
Al2Se3 is your chemical formula
Hope this helps
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-Kayla <3
An organism that has two different alleles for a trait is called heterogeneous
The mass of a chemical substance is known as the atomic number or atomic mass
Simple...
moving along the periodic table ---->>>
Oxygen has 6.
Nitrogen has 5.
Sodium has 1.
Neon has 8.
Thus, your answer, Oxygen.
