Problem 133 - A Complete Resource Book in Chemistry for JEE Main

Question

Match the following: List-I List-II 1\. Beryl (i) \(\mathrm{KCl} \cdot \mathrm{MgCl}_{2} .6 \mathrm{H}_{2} \mathrm{O}\) 2\. Carnalite (ii) \(\mathrm{MgCO}_{3}\) 3\. Asbestos (iii) \(3 \mathrm{BeO} \cdot \mathrm{Al}_{2} \mathrm{O}_{3} \cdot 6 \mathrm{SiO}_{2}\) 4\. Magnesite (iv) \(\mathrm{Ca}_{2} \mathrm{Mg}_{5} \mathrm{Si}_{8} \mathrm{O}_{22}(\mathrm{OH})_{2}\) (v) \(\mathrm{CaSO}_{4} \cdot 2 \mathrm{H}_{2} \mathrm{O}\) The correct matching is: \(\begin{array}{lll}1 & 2 & 3\end{array}\) 4 (a) (iii) (iv) (i) (ii) (b) (iv) (iii) (ii) (i) (c) (iii) (i) (iv) (ii) (d) (iii) (i) (ii) (iv)

Step-by-Step Solution

Answer

The correct matching is option (c): 1-(iii), 2-(i), 3-(iv), 4-(ii).

Step 1: Examine Beryl

First, examine the compound Beryl from List-I. According to its chemical formula given: \(3 \mathrm{BeO} \cdot \mathrm{Al}_{2} \mathrm{O}_{3} \cdot 6 \mathrm{SiO}_{2}\). Match this formula with the options in List-II. It matches option (iii).

Step 2: Examine Carnalite

Next, examine Carnalite from List-I. The chemical formula for Carnalite is \(\mathrm{KCl} \cdot \mathrm{MgCl}_{2} .6 \mathrm{H}_{2} \mathrm{O}\). This matches option (i) in List-II.

Step 3: Examine Asbestos

Now, look at Asbestos from List-I. The formula for Asbestos is given as \(\mathrm{Ca}_{2} \mathrm{Mg}_{5} \mathrm{Si}_{8} \mathrm{O}_{22}(\mathrm{OH})_{2}\). This corresponds to option (iv) in List-II.

Step 4: Examine Magnesite

Finally, examine Magnesite from List-I. The chemical formula for Magnesite is \(\mathrm{MgCO}_{3}\) which matches with option (ii) in List-II.

Key Concepts

Beryl

Beryl is a fascinating mineral that belongs to the silicate family and is known for its beautiful crystals, often used in jewelry.
Its chemical formula is \[3 \text{BeO} \cdot \text{Al}_2 \text{O}_3 \cdot 6 \text{SiO}_2 \] This reflects its complex structure composed of beryllium, aluminum, and silicon oxides.
Beryl comes in various colors, depending on the trace impurities it contains, and includes well-known gemstones like emerald and aquamarine.

• Emeralds are green due to chromium and sometimes vanadium.
• Aquamarine is pale blue, often colored by iron.

When identifying Beryl, its hardness, vitreous luster, and hexagonal crystal structure are key characteristics. Understanding its chemical formula is crucial, as it highlights the mineral's unique composition and its geological significance.

Chemical Formulas

Chemical formulas play a vital role in inorganic chemistry as they provide a concise way to represent chemical substances.
They tell us which elements are present in a compound and in what proportions.
For example, the formula \[\text{KCl} \cdot \text{MgCl}_{2} \cdot 6 \text{H}_2 \text{O}\] indicates that Carnalite consists of potassium chloride, magnesium chloride, and water molecules.

• Each element in the formula is represented by its chemical symbol from the periodic table.
• The subscript numbers indicate the number of atoms of each element in a molecule or compound.
• Parentheses are sometimes used to show groups of atoms that appear more than once.

Understanding chemical formulas is essential for correctly identifying minerals and predicting their chemical reactions.

Minerals Identification

Minerals are the building blocks of rocks and are identified based on their chemical composition and physical properties.
Accurate identification is essential for various applications, including geology, gemology, and materials science.
Here's how the identification process typically works:

• Observation of physical properties such as color, luster, and crystal form.
• Determination of hardness using the Mohs scale.
• Analysis of chemical formulas to understand the elemental components.

For instance, identifying Asbestos from its formula \[\text{Ca}_2 \text{Mg}_5 \text{Si}_8 \text{O}_{22}(\text{OH})_2\] shows it is composed of calcium, magnesium, silicon, and oxygen, with a hydroxide group.
Correct identification not only helps in academic research but also enhances industrial applications, ensuring materials are used appropriately.