MCQ Detailed View

Copper sulfate is an important inorganic compound widely recognized in chemistry. Its correct formula is CuSO₄·5H₂O, known as Copper(II) sulfate pentahydrate. The compound consists of one copper ion (Cu²⁺), one sulfate ion (SO₄²⁻), and five molecules of water of crystallization. These water molecules are responsible for its characteristic bright blue crystalline appearance, which is why the compound is commonly called Blue Vitriol or Blue Stone.

When copper sulfate crystals are heated strongly, they lose their water of crystallization. This process converts the blue crystalline form into a white powder, known as anhydrous copper sulfate (CuSO₄). This property makes copper sulfate a useful reagent in laboratories, particularly for detecting the presence of water. Anhydrous CuSO₄ readily absorbs moisture and turns blue again, making it a reliable test for water.

Copper sulfate has a wide range of uses. In agriculture, it is applied as a fungicide, herbicide, and pesticide. It is also used to prepare Bordeaux mixture, a well-known fungicidal spray for protecting crops. In industries, it is utilized in electroplating, textile dyeing, and as a mordant. In education and laboratories, it plays an important role in experiments such as the Biuret test for proteins and as a reagent in chemical analysis.

Looking at the incorrect options: CuSO₃·4H₂O and CuSO₃·5H₂O are not correct, as copper sulfite (CuSO₃) is not commonly stable in this hydrated form. CuSO₄·4H₂O is also incorrect because the most common stable hydrate is with five water molecules, not four. Therefore, the correct formula for Copper Sulfate is CuSO₄·5H₂O.