The compound with the formula NH42SO4 is called Ammonium Sulfate.
To break it down further, the NH4 represents the ammonium ion, which carries a positive charge. When there are two ammonium ions, as indicated by the subscript ‘2’, the total positive charge contributed by ammonium is +2. On the other hand, SO4 represents the sulfate ion, which has a charge of -2. When these ions combine, they balance each other out, resulting in a neutral compound. Therefore, the name Ammonium Sulfate accurately describes what NH42SO4 is.