Problem 37 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

Match the following, choosing one item from column \(\mathbf{X}\) and one from column Y. [Multiple Concepts, 1982 - 2 Marks] \(\mathbf{X} \quad \mathbf{Y}\) (i) neutrons (p) Kohlrausch (ii) molecular speed (q) van der Waals (iii) intermolecular forces (r) Maxwell (iv) conductance of ions (s) Chadwick

Step-by-Step Solution

Answer

(i) neutrons - (s) Chadwick, (ii) molecular speed - (r) Maxwell, (iii) intermolecular forces - (q) van der Waals, (iv) conductance of ions - (p) Kohlrausch.

Step 1: Understanding Neutrons

In this step, we need to find the right match for neutrons in column Y. Neutrons are subatomic particles discovered by James Chadwick in 1932. Therefore, the correct match for neutrons is (s) Chadwick.

Step 2: Understanding Molecular Speed

Next, we consider molecular speed and its theories. James Clerk Maxwell is known for formulating the kinetic theory which includes molecular speed. Thus, the correct match is (r) Maxwell.

Step 3: Understanding Intermolecular Forces

Intermolecular forces deal with interactions between molecules, which are part of theories developed by Johannes Diderik van der Waals. Hence, we match intermolecular forces with (q) van der Waals.

Step 4: Understanding Conductance of Ions

Conductance of ions in solutions is described by the law formulated by Friedrich Kohlrausch, known as Kohlrausch's law. Therefore, conductance of ions matches with (p) Kohlrausch.

Key Concepts

Neutrons

Neutrons are fundamental particles found in the nucleus of an atom, playing a crucial role in its stability. Unlike protons, which have a positive charge, neutrons are electrically neutral, meaning they have no charge. This neutrality gives them their name. James Chadwick discovered neutrons in 1932, a breakthrough that revolutionized our understanding of atomic structure. Neutrons, along with protons, are called nucleons, and they bind together in the atomic nucleus through the strong nuclear force. This force is one of the fundamental interactions in nature. Neutrons help buffer the protons in the nucleus, keeping the atom stable by offsetting the repulsion between positively charged protons.

Molecular Speed

Molecular speed is an integral concept in understanding the behavior of gases. It is closely linked to the kinetic molecular theory, which was greatly developed by James Clerk Maxwell and Ludwig Boltzmann. This theory describes how the microscopic behaviors of atoms and molecules affect the macroscopic properties of gases, such as pressure and temperature.
The molecular speed depends on a few factors:

• The temperature of the gas: Higher temperatures increase molecular speed.
• The mass of the molecules: Lighter molecules move faster.

The distribution of molecular speeds in a gas is depicted by what is known as the Maxwell-Boltzmann distribution. This distribution shows that in a gas, while most molecules move at an average speed, there is a range of speeds present, from very slow to very fast.

Intermolecular Forces

Intermolecular forces are the forces of attraction and repulsion between interacting particles (atoms and molecules). These forces are critical for determining the physical properties of substances, such as melting and boiling points. Johannes Diderik van der Waals contributed significantly to our understanding of these forces.
There are several types of intermolecular forces:

• Van der Waals forces: Includes both dipole-dipole interactions and London dispersion forces.
• Hydrogen bonding: A particularly strong form of dipole-dipole interaction involving hydrogen.

These forces are much weaker compared to intramolecular forces, like covalent bonds. However, they are crucial for the existence of condensed phases (liquids and solids) and for the functionality of biological molecules.

Conductance of Ions

The conductance of ions is a measure of a solution's ability to conduct electricity, and it reflects the movement of ions within that solution. Friedrich Kohlrausch was a pioneer in this field, and he formulated what is known as Kohlrausch's Law. This law describes how ionic conductivity is related to the nature and concentration of ions in a solution.
Ionic conductance depends on:

• The concentration of electrolytes: Higher concentration generally increases conductance.
• The type of ions present: Different ions have varying abilities to move through a solution.

Conductance is particularly important in electrochemistry and analytical chemistry, helping in understanding how well solutions can transport electricity and allowing for the characterization of ion behaviors in solutions.