Science

Students can check Class 12 Chemistry Chapter 9 Amines NCERT Solutions, which can help you know name chemical reactions crucial for CBSE Board Exams and Competitive Exams like JEE and NEET:

• Gabriel Phthalimide Synthesis – Used to prepare primary amines from phthalimide via hydrolysis.

• Hoffmann Bromamide Degradation Reaction – Converts amides to primary amines with one less carbon atom using Br? and NaOH.

• Carbylamine Reaction – A test for primary amines where they react with chloroform and KOH to form isocyanides (foul-smelling).

• Acylation and Alkylation of Amines – Involves the reaction of amines with acid chlorides or alkyl halides.

• Coupling Reaction – Aryldiazonium salts react with phenols or aromatic amines to form azo dyes.

The chapter consists of fundamental topics that are important for board exams preparation as well as for competitive tests: 

• Composition and Size of the Nucleus: Understanding protons, neutrons, and nuclear density.

• Nuclear Force: The forces that hold the nucleus together. 

• Mass-Energy Equivalence (E = mc²): Einstein's equation and its significance in nuclear reactions.

• Nuclear Binding Energy: Understanding nuclear stability and energy release. 

• Radioactivity: Concepts of alpha, beta, and gamma decay. 

• Laws of Radioactive Decay: Half-life, mean life, and decay constant derivations. 

• Nuclear Fission and Fusion: Their role in power generation and astrophysical processes.

• Applications of Nuclear Physics: Uses of radioisotopes in medicine, industry, and archaeology.

While studying the mechanical properties of solids, stress and strain are fundamental concepts.

Stress: It refers to the condition when the external force is applied to a solid body and it experiences an internal restoring force per unit area. The resisting deformation due to the internal force is called stress. The formula is:

The SI unit of stress is N/m² (Pascal, Pa).

There are three types of stress -

1. When the applied force increases the length of the body, it is called tensile stress.
2. When the applied force decreases the length of the body, it is termed as the compressive stress.
3. When the force is applied tangentially and creates deformation in shape, it is called shear stress.

Strain: It is a dimension less quantity. It refers to the relative deformation produced in a body due to applied stress. The formula is:

There are three types of strain:

1. Change in length per unit original length is called the Longitudinal Strain.
2. The change in volume per unit original volume is called the Volumetric Strain.
3. Angular deformation due to shear stress is called Shear Strain.

Hooke's Law relates stress and strain by a formula. It states that within the elastic limit, stress is directly proportional to strain:

E stands for the modulus of elasticity.