What is the correct molecular formula for the compound magnesium chromate pentahydrate?

Magnesium forms Mg²⁺, and chromate is CrO₄²⁻, so they combine in a 1:1 ratio to make MgCrO₄. “Pentahydrate” means five water molecules are included, giving MgCrO₄•5H₂O. Therefore, the correct choice is B, MgCrO₄•5H₂O.

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