Which substance will conduct electric current in the solid state? (a) Diamond (b) Graphite (c) Sodium chloride (d) Iodine

Carbon is unique among the elements in its ability to form strongly bonded chains, sealed off by hydrogen atoms. Its allotropes—different forms of the same element with distinct structures and properties—are diamond, graphite, and amorphous forms like coal and soot. Diamond is renowned for its hardness due to a tetrahedral arrangement of the carbon atoms where electrons are not free to move. This means that although it's a good thermal conductor, diamonds cannot conduct electricity.

In stark contrast, graphite is composed of layers of carbon atoms arranged in a hexagonal lattice. Between these layers, electrons are delocalized and can move freely, making graphite a good electrical conductor. This property is key in applications such as battery electrodes and as a lubricant. Understanding these differences helps students, especially those preparing for competitive exams like NEET Chemistry, to better appreciate the versatile nature of carbon's bonding and the resulting electrical conductivity.

Ionic compounds, such as sodium chloride, are formed from strong electrostatic interactions between ions. In their solid state, these ions are locked in place within a crystal lattice structure and are unable to move freely; this immobility results in the lack of electrical conductivity. However, when ionic compounds are dissolved in water or melt, the lattice breaks down, and the ions are free to move. This results in an electrically conductive solution or liquid. For NEET Chemistry aspirants, the understanding of these physical changes and their influence on electrical conductivity is fundamental.

Moreover, recognizing that ionic compounds only conduct electricity when the ions are mobile is a critical point that appears frequently in different concepts of chemistry. This distinction is often tested in exams and is a frequent source of confusion for students.

Electrical conductivity in solids is primarily based on the availability of charge carriers, which can be either electrons or ions. Metals have valence electrons that are not bound to any particular atom and can move freely through the metal. In contrast, ionic compounds conduct electricity in their liquid state or when dissolved because ions act as charge carriers.

Understanding electrical conductivity involves exploring these charge carriers and their mobility. For example, in graphite, the delocalized electrons make it a good conductor. Educational platforms frequently aim to clarify these concepts with lucid explanations and examples, making them accessible to students with various levels of understanding. Such knowledge is not only essential for NEET Chemistry but also for foundational learning in physics and engineering disciplines.

The National Eligibility cum Entrance Test (NEET) is a highly competitive exam in India for students who wish to pursue undergraduate medical courses. Chemistry is a significant portion of the exam, with questions that often assess a student's comprehension of chemical properties and reactions, including electrical conductivity. A solid grip on topics like the electrical conductivity properties of different substances, including the allotropes of carbon and the nature of ionic compounds, is crucial for scoring well in NEET Chemistry.

The examination requires not only memorization but also the ability to apply concepts to various scenarios. Therefore, resources that offer clear explanations and relate concepts to real-world applications are invaluable for NEET aspirants. This holistic understanding aids in developing problem-solving skills necessary for the exam and for future academic and professional pursuits in the field of chemistry.