I'm assuming you mean the molecular compound H 3 O and it's name is Hydronium. Hope this helps :)
H 3 O is called Hydronium ion. It is obtained when water is acidic.
The given name of H 3 O is hydronium. Hydronium ion is formed when a proton combines with a water molecule, and it plays a significant role in acid-base chemistry and pH levels. As such, the concentration of hydronium ions reflects the acidity of a solution.
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