Answer the question on basis of passage given below:

P block elements are placed in groups 13 to 18 of the periodic table. Their valence shell electronic configuration is \(ns^2\, \ np^{1-6}\). Group 16 of of the p-block elements are known as the group of chalcogens having \(ns^2\, \ np^4\) as their general electronic configuration. They exhibit number of oxidation states but the stability of \(-2\) oxidation state decreases down the group. They are sometimes also known as group of chalcogens as the name is derived from the Greek word for brass and points to the association of sulphur and its congeners with copper. Their ionization enthalpy decreases down the group. Oxygen shows anomalous behaviour due to its small size and high electronegativity.

Identify the epsom salt out of the following salts:

\(MgSO_4 .7H_2O\)

The correct answer is option 4. \(MgSO_4 .7H_2O\).

Let us delve into the identification of Epsom salt and why the correct choice is \(MgSO_4 \cdot 7H_2O\):

Epsom Salt:

Chemical Formula: \(MgSO_4 \cdot 7H_2O\)

Components:

\(MgSO_4\): Magnesium sulfate

(7H_2O\): Seven water molecules of hydration

Properties and Uses:

Appearance: Epsom salt typically appears as a white, crystalline solid.

Uses:

Medical: Used in baths to relieve sore muscles.

Laxative: Can be used in small quantities as a laxative.

Gardening: Enhances the growth of plants by providing magnesium and sulfur.

Analysis of the Given Salts

Option 1: \(PbS\) (Lead(II) Sulfide)

Lead(II) sulfide is a compound of lead and sulfur. It is used in the production of lead and in various industrial applications but is not related to Epsom salt.

Option 2: \(ZnS\) (Zinc Sulfide)

Zinc sulfide is a compound of zinc and sulfur. It is used in luminescent materials and pigments but is not Epsom salt.

Option 3: \(CuFeS_2\) (Chalcopyrite)

Chalcopyrite is a copper-iron sulfide mineral and is an important ore of copper. It is not Epsom salt.

Option 4: \(MgSO_4 \cdot 7H_2O\) (Magnesium Sulfate Heptahydrate)

This is Epsom salt. It is composed of magnesium sulfate with seven water molecules of hydration. The presence of these water molecules differentiates it from anhydrous magnesium sulfate (\(MgSO_4\)).

Why Option 4 is Correct:

Magnesium Sulfate Heptahydrate (\(MgSO_4 \cdot 7H_2O\)):

Composition: Contains magnesium, sulfur, and oxygen, with the addition of seven water molecules.

Hydration: The seven water molecules contribute to its crystalline form and its ability to dissolve in water.

Identification: The formula \(MgSO_4 \cdot 7H_2O\) matches exactly with the chemical formula for Epsom salt.

Summary

The correct identification of Epsom salt among the given options is: 4. \(MgSO_4 \cdot 7H_2O\)

This is because it accurately reflects the chemical structure and properties of Epsom salt.