Science

Energy bands refer to how electrons behave in solids. In the case of conductors where the conductivity is high, the valence band and conduction band overlap which lets the electrons move freely. In the case of semiconductors, the valence and conduction bands have a small energy gap between them such as ?1 eV. There is a requirement for some external energy for electrons to jump to the conduction band. The gap is large in the case of insulators (>3 eV), making the electron movement nearly impossible. The energy band model differentiates how easily a material can conduct electricity. In semiconductors, there is controlled conductivity which is important for electronic devices as in these cases light or thermal energy can excite electrons.

According to the NCERT Solutions for Class 12 Physics Chapter 14 Semiconductor Electronics, intrinsic semiconductors are pure forms of semiconductor materials with no impurities like germanium or silicon. At room temperature, their conductivity is very low because they are solely based on thermally generated charge carriers (electrons and holes). On the other hand, extrinsic semiconductors to increase the conductivity, they are doped with impurities. P-type are doped with trivalent atoms (extra holes) and N-type semiconductors are doped with pentavalent atoms (extra electrons).
Doping makes extrinsic semiconductors far more conductive by enhancing the number of charge carriers. It becomes more practical for electronic devices like transistors, diodes, and integrated circuits.

A transistor can either be NPN or PNP. It is a three-layer semiconductor device with three terminals—emitter, base, and collector.  In the case of the NPN transistor, there is a larger current from the collector to the emitter due to a small current at the base. It involves an amplification property which is key to the function of the NPN transistor. A transistor can be used in two main modes - as switches in microcontrollers, and computers and as amplifiers in speakers and radios etc. These are foundational in digital and analogue circuits due to their ability to control current. Transistors form the backbone of the integrated circuits and modern electronics.

Energy bands refer to how electrons behave in solids. In the case of conductors where the conductivity is high, the valence band and conduction band overlap which lets the electrons move freely. In the case of semiconductors, the valence and conduction bands have a small energy gap between them such as ?1 eV. There is a requirement for some external energy for electrons to jump to the conduction band. The gap is large in the case of insulators (>3 eV), making the electron movement nearly impossible. The energy band model differentiates how easily a material can conduct electricity. In semiconductors, there is controlled conductivity which is important for electronic devices as in these cases light or thermal energy can excite electrons.

According to the NCERT Solutions for Class 12 Physics Chapter 14 Semiconductor Electronics, intrinsic semiconductors are pure forms of semiconductor materials with no impurities like germanium or silicon. At room temperature, their conductivity is very low because they are solely based on thermally generated charge carriers (electrons and holes). On the other hand, extrinsic semiconductors to increase the conductivity, they are doped with impurities. P-type are doped with trivalent atoms (extra holes) and N-type semiconductors are doped with pentavalent atoms (extra electrons).
Doping makes extrinsic semiconductors far more conductive by enhancing the number of charge carriers. It becomes more practical for electronic devices like transistors, diodes, and integrated circuits.

Students ask this question many a times that wehter NCERT are enough or they should follow other reference books. Students should use NCERT books for CBSE Class 12 board exams, NCERT is more than sufficient for mastering the Biomolecules chapter. All key concepts, definitions, and reactions asked in the exams are directly covered in the textbook, WE have provided NCERT Solutions for Class 12 chemistry Biomolecules. 

However, for competitive exams like NEET and JEE, while NCERT remains the primary reference, students should also solve additional MCQs from reference books like MTG NCERT at Your Fingertips, NCERT Exemplar, or practice modules by coaching institutes. These help build speed, accuracy, and deeper conceptual clarity. Understanding NCERT thoroughly and then practicing higher-level application-based questions is the best strategy for excelling in both boards and competitive exams.

Chapter 10 Biomolecules of Class 12 Chemistry includes several important topics which are frequently asked in the state and cbses board exams. The most important topics in the Biomolecules chapter include the classification and structure of carbohydrates (monosaccharides, disaccharides, polysaccharides), amino acids and proteins (including peptide bond formation), enzymes and their characteristics, nucleic acids (DNA and RNA structure and components), and vitamins with their types and deficiencies.

Questions often focus on structural identification, naming, and functions of biomolecules, as well as simple reactions like hydrolysis and oxidation. Students should also pay attention to zwitterion structure in amino acids, enzyme action mechanisms, and differences between DNA and RNA. Students must practice diagrams and learn key functions of each biomolecule to score full marks in this chapter. Students can take help of NCERT Solutioins for Class 12 Chemistry Biomolecules to get good understanding of the concepts and requirements.

Biomolecules are organic compounds essential to life, found in all living organisms. Biomolecules include carbohydrates, proteins, lipids, nucleic acids, enzymes, and vitamins.

NCERT Class 12 Chemistry chapter 10 Biomolecules covers the molecular basis of life, including the structure, types, and functions of each biomolecule. This chapter is important because it connects chemistry to biology and helps students understand metabolism, heredity, and biochemical reactions. It also forms the foundation for higher studies in medicine, biochemistry, and biotechnology. Biomolecules are also frequently tested in CBSE board exams and competitive exams like NEET and JEE, making it a crucial topic to master.