NCERT Class 12 Notes

NCERT offers the foundation for every class 12 student. CBSE board exam questions are primarily based on the NCERT exercise, Examples and conceptual explanation.

There are various benefits of using NCERT Solutions. 

• Specially for CBSE Board students, these NCERT Solutions are the best resource to prepare for the boards.
• These NCERT Solutions include step-wise descriptive answer approach that will help you write good answers.
• These solutions also help you understand problem-solving and how to approach a specific type of conceptual or numerical problem.
• If you are preparing for the JEE or NEEt exam, these solutions can be your first decisive step towards success.
• For NEET and JEE aspirants, NCERT solutions are the first foundation block that offer understanding of fundamental concepts, their application

Shiksha provides NCERT Notes for all class 11 and 12 important topics. We have covered all concepts in detail. You can check the key characteristics below;

• We have covered the topic-wise NCERT Notes of all NCERT textbook chapters, including deleted topics and chapters. 
• These NCERT Notes are prepared keeping in mind the CBSE Exam pattern and CBSE syllabus 2025-2026.
• We have designed these NCERT Notes as revision notes along with a concise summary.
• You will also get the NCERT-based definition and derivation along with basic problem-solving techniques.
• We have also included solved JEE and NEET questions for holistic topic and in-depth conceptual coverage.

We know that nucleic acids are biomolecules which is responsible for carrying the genetic information in living organisms. Nucleic acids have various properties, including physical, chemical and biological properties. 

Physical Properties

Nucleic acids are macromolecular in nature because they have a high molecular weight. They are water-soluble but insoluble in alcohol. Also, nucleic acids can absorb ultraviolet light at 260 nm because they have nitrogenous bases.

Chemical Properties

• Acidic in nature
• Hydrolysis
• Base pairing
• Negative charging

Biological Properties

• Stores and transfers genetic information
• The genetic code of every organism is unique. This code is decided by the sequence of bases.
• DNA makes its own copy.

The nature of bonding in Ni (CO)? includes synergic bonding. The synergic bonding in metal carbonyls like nickel tetracarbonyl is due to two-way interaction of metal and carbonyl ligand electron density donation.

The synergic bonding is best explained thorugh Molecular Orbital Theory (MOT), which explains the donation of electron density from the filled d-orbitals of nickel (Ni) into the antibonding? * orbitals of the carbon monoxide (CO) ligand.

The synergic bonding can be described as a combination of? -bond formation due to donation of lone pair to metal center, and? back-bond formation due to donation of lone pair to CO ligand. 

The metal-carbon bonds (M-C) in metal carbonyls are due to the synergic interaction between the metal and carbonyl group. There are two types of bonding between metal and carbonyl group. 

? -bond in Metal Carbonyls: The Carbonyl (CO) ligand donates a lone pair of electrons to the metal center to fill its empty d-filled orbital. This electron density donation is called? -donation.

? -back bond in Metal Carbonyls: This is the case of back bonding. The already filled d-orbitals return the electron density into the empty? * (antibonding) orbital of CO. This electron density donation by the metal is called? -back donation.

Both these combined? -bonding and? -back bonding are called synergic bonding.