enow.com Web Search

Search results

  1. Results from the WOW.Com Content Network
  2. 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.

  3. Mesomeric effect - Wikipedia

    en.wikipedia.org/wiki/Mesomeric_effect

    In chemistry, the mesomeric effect (or resonance effect) is a property of substituents or functional groups in a chemical compound. It is defined as the polarity produced in the molecule by the interaction of two pi bonds or between a pi bond and lone pair of electrons present on an adjacent atom. [ 1 ]

  4. Resonance (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Resonance_(chemistry)

    Contributing structures of the carbonate ion. In chemistry, resonance, also called mesomerism, is a way of describing bonding in certain molecules or polyatomic ions by the combination of several contributing structures (or forms, [1] also variously known as resonance structures or canonical structures) into a resonance hybrid (or hybrid structure) in valence bond theory.

  5. Joint Entrance Examination – Advanced - Wikipedia

    en.wikipedia.org/wiki/Joint_Entrance_Examination...

    The IIT-JEE was first conducted in 1961 as Common Entrance Exam (CEE), coinciding with the 1961 IIT Act. [11] In 1978, the English paper was not considered when ranking participants' performance in the examination. In 1998, the English test was discontinued. In 1997, the IIT-JEE was conducted twice after the question paper was leaked in some ...

  6. Resonance - Wikipedia

    en.wikipedia.org/wiki/Resonance

    However, resonance can also be detrimental, leading to excessive vibrations or even structural failure in some cases. [3] All systems, including molecular systems and particles, tend to vibrate at a natural frequency depending upon their structure; this frequency is known as a resonant frequency or resonance frequency.

  7. Bent's rule - Wikipedia

    en.wikipedia.org/wiki/Bent's_rule

    The inductive effect is the transmission of charge through covalent bonds and Bent's rule provides a mechanism for such results via differences in hybridisation. In the table below, [ 26 ] as the groups bonded to the central carbon become more electronegative, the central carbon becomes more electron-withdrawing as measured by the polar ...

  8. Nucleophilic aromatic substitution - Wikipedia

    en.wikipedia.org/wiki/Nucleophilic_aromatic...

    Since the nitro group is an activator toward nucleophilic substitution, and a meta director, it is able to stabilize the additional electron density (via resonance) when the aromatic compound is attacked by the hydroxide nucleophile.

  9. Conjugated system - Wikipedia

    en.wikipedia.org/wiki/Conjugated_system

    Cinnamaldehyde is a naturally-occurring compound that has a conjugated system penta-1,3-diene is a molecule with a conjugated system Diazomethane conjugated pi-system. In theoretical chemistry, a conjugated system is a system of connected p-orbitals with delocalized electrons in a molecule, which in general lowers the overall energy of the molecule and increases stability.