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  2. IISER Aptitude Test - Wikipedia

    en.wikipedia.org/wiki/IISER_Aptitude_Test

    IAT consists of 60 questions: 15 questions each from Biology, Chemistry, Mathematics, and Physics. Total time for answering the test is 3 hours. Questions are of multiple choice type with only one correct answer. Each correct answer is awarded 4 marks. Each incorrect answer leads to the deduction of 1 mark. Unanswered questions are awarded 0 mark.

  3. Bent's rule - Wikipedia

    en.wikipedia.org/wiki/Bent's_rule

    For a tetrahedral molecule such as difluoromethane with two types of atom bonded to the central atom, the C-F bond to the more electronegative substituent (F) will involve a carbon orbital with less s character than the C-H bond, so that the angle between the C-F bonds is less than the tetrahedral bond angle of 109.5°. [15] [23]

  4. Atom - Wikipedia

    en.wikipedia.org/wiki/Atom

    An atom consists of a nucleus of protons and generally neutrons, surrounded by an electromagnetically bound swarm of electrons. The chemical elements are distinguished from each other by the number of protons that are in their atoms. For example, any atom that contains 11 protons is sodium, and any atom that contains 29 protons is copper.

  5. Spiro compound - Wikipedia

    en.wikipedia.org/wiki/Spiro_compound

    The common atom that connects the two (or sometimes three) rings is called the spiro atom. [2]: SP-0 In carbocyclic spiro compounds like spiro[5.5]undecane, the spiro-atom is a quaternary carbon , and as the -ane ending implies, these are the types of molecules to which the name spirane was first applied (though it is now used general of all ...

  6. Chemical structure - Wikipedia

    en.wikipedia.org/wiki/Chemical_structure

    Theories of chemical structure were first developed by August Kekulé, Archibald Scott Couper, and Aleksandr Butlerov, among others, from about 1858. [4] These theories were first to state that chemical compounds are not a random cluster of atoms and functional groups, but rather had a definite order defined by the valency of the atoms composing the molecule, giving the molecules a three ...

  7. Electron configuration - Wikipedia

    en.wikipedia.org/wiki/Electron_configuration

    In atomic physics and quantum chemistry, the electron configuration is the distribution of electrons of an atom or molecule (or other physical structure) in atomic or molecular orbitals. [1] For example, the electron configuration of the neon atom is 1s 2 2s 2 2p 6 , meaning that the 1s, 2s, and 2p subshells are occupied by two, two, and six ...

  8. Shape of the atomic nucleus - Wikipedia

    en.wikipedia.org/wiki/Shape_of_the_atomic_nucleus

    The atomic nucleus is composed of protons and neutrons (collectively called nucleons). In the Standard model of particle physics, nucleons are in the group called hadrons, the smallest known particles in the universe to have measurable size and shape. [1]

  9. Joint Entrance Examination - Wikipedia

    en.wikipedia.org/wiki/Joint_Entrance_Examination

    JEE-Main, unlike JEE-Advanced, has a fixed exam structure and is not subject to change every year. Up until 2018, the JEE-Main Paper-I was three hours long and consisted of thirty questions in each of the three subjects (physics, chemistry and maths). 4 marks are awarded for correct answers and 1 mark is deducted for incorrect answers.