Class 12th Cbse Boards @cbse_boards_class_12_2025 Channel on Telegram

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Class 12th Cbse Boards (English)

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Class 12th Cbse Boards

24 Oct, 13:36


Organic Chemistry Full Chapter Notes

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Class 12th Cbse Boards

23 Oct, 15:03


CBSE 2025 SYLLABUS

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Class 12th Cbse Boards

18 Oct, 17:45


Chemistry Important MCQs

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13 Oct, 15:45


Poetic Devices❤️

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12 Oct, 05:00


Chemistry Formula Booklet ❤️

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08 Oct, 12:56


Chemistry Formula Booklet ❤️

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06 Oct, 12:32


Biomolecules Important Questions❤️

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03 Oct, 11:31


Organic Chemistry Name Reactions❤️

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01 Oct, 11:31


Aldehyde Ketone & Carboxylic Acid Important Questions❤️

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29 Sep, 11:31


Electromagnetic Waves Important Questions❤️

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27 Sep, 07:17


Chemistry Formula Booklet ❤️

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25 Sep, 13:02


Coordination Compounds Important Questions❤️

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24 Sep, 11:30


Poetic Devices❤️

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22 Sep, 15:03


Alternating Current Handwritten Short Notes ❤️

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21 Sep, 16:35


Physics Derivations ❤️

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20 Sep, 12:30


Modern Physics Handwritten Short Notes

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19 Sep, 16:53


Complete Optics Handwritten Short Notes ❤️

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Class 12th Cbse Boards

21 Aug, 17:00


IMPORTANT Years In NCERT :-

1731 - Many people of Bishnoi community sacrifice their lives saving trees (Jodhpur)

1770 - Priestley's experiment by Bell Jar, Mice & Mint plant, Candle.

1774 - Discovery of oxygen by Joseph Priestley

1838 - Matthias Schleiden-Cell Theory                                                   

1829 - Theodore Schwann- Cell Theory

1850sBefore industrialization => more white wing Moth

1854 - Julius von Sachs proved that glucose is formed in photosynthesis & stored as starch.

1855 - "Omnis cellula cellula" by Rudolf Virchow & complete the cell theory.

1856 - 1863 Mendel work on garden pea.

1860 - Hydroponics technique developed by Julie Von Sache

1865 - Mendel publishes his workon inheritance of character

1866 - Down's Syndrome discovered by Langdon Down.

1869 - DNA as a acidic substance was 1st identified by Friedrich Meischer & termed a "Nuclein"

1891 - Fossils of Java man discovered in Java
          - Henking discovered X-body (X-chromosome) in insect. (XO- type sex determination
)

1892 - Discovery of TMV by D.J. Ivanowsky

1898M.W. Beijerinck demonstrated infectious nature of TMV
          - Discovery of Golgi Body by Camillo Golgi
.

1900 - Rediscovery of Mendel's work by ---> • Hugo de Vries
           • Karl Corrence
           • Tschemark


1902 - Chromosomal theory of inheritance given by Sutton & Bovery.

1905 - Law of limiting factors for plants given by Blackmann

1920 - After Industrialisation => more black moth

1928 - Frederick Griffith's Transformation  experiment on Streptococcus pneumonia bacteria

1933 – 1944 - Avery, Macleod McCarty used transformation principle of Griffith's experiment & concluded that DNA is genetic material.

1938 - Coelacanth/Lobe Fines caught in South Africa ---> Ancestor of amphibia.

1947 - At the time of our independence India's population, was approximately 350 million .

1950Electron microscope invention
            -  Tissue culture started


1951 - Family planning was initiated

1952 - Hershey & Chase experiment more correctly proved that DNA ie genetic material [ unquivocal_proof ]

1953  - Discovery of ribosome by George Palade.
          - S.L Miller Experiment of evolution.
          - Double helical structure model of DNA given by Watson & Crick
.

1958 - Matthew Meselson of Franklin Stahl experiment (E. coli in NH4CI medium) proved that DNA replication is semiconservative )
         -  Taylor study on vicia faba plant (used radioactive thymidind and proved  semiconservative nature of DNA)


1960Green Revolution.

1963 - Restriction endonuclease isolated from E. coli.

1963 - Wheat varieties Sonalika f Kalyan Sona (High yield & Disease resistant ) introduced in INDIA

1966 - Derived semi dwarf varieties of rice introduced in India.

1969 - R.H. Whittaker proposed FIVE-KINGDOM Classification

1971 - Discovery of viroids by T.O. Diener
          -  Govt. of India legalised MTP.


1972 - Fluid Mosaic model of plasma membrane by Singer & Nicolson
          - 1st recombinant DNA developed by Stanley Cohen and Herbert Boyer
          - National committee for environmental planning and Coordination was established.
          - Wild life protection act in India.

1974Water Act.  &  also Chipko movement

1980Joint Forest movement

1981 - Air act.
           - AIDS was fired reported
           - Intrinsic growth rate of India (r= 0.0205)
 

1983 - Eli Lilly American company human Insulin from E. coli.

1984 - Bhopal Tragedy
          - Ministry of Environment amd Forest
.

1986 - Environment Act (NEPA)

1987 - Noise included in air pollution  
          - Montreal protocol (Canada
)

1988 - National Forest Policy

1989Montreal Protocol became effective.

1990Delhi ranked 4th among 41 most polluted cities.

1990 - First clinical gene therapy was given to 14 yr old girl with ADA deficiency eye.
- Human Genome Project (HGP) launched.