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  2. Past paper - Wikipedia

    en.wikipedia.org/wiki/Past_paper

    A past paper is an examination paper from a previous year or previous years, usually used either for exam practice or for tests such as University of Oxford, [1] [2] University of Cambridge [3] College Collections. Exam candidates find past papers valuable in test preparation.

  3. Pyridinium chlorochromate - Wikipedia

    en.wikipedia.org/wiki/Pyridinium_chlorochromate

    Pyridinium chlorochromate in a vial. Pyridinium chlorochromate (PCC) is a yellow-orange salt with the formula [C 5 H 5 NH] + [CrO 3 Cl] −.It is a reagent in organic synthesis used primarily for oxidation of alcohols to form carbonyls.

  4. List of important publications in chemistry - Wikipedia

    en.wikipedia.org/wiki/List_of_important...

    Aside from being one of the first chemistry textbooks, the book was one of the first to state the Law of conservation of mass, define a chemical element, and contain a list of known elements. [10] [3]: 154 [11]: 410

  5. AP Chemistry - Wikipedia

    en.wikipedia.org/wiki/AP_Chemistry

    The 2014 AP Chemistry exam was the first administration of a redesigned test as a result of a redesigning of the AP Chemistry course. The exam format is now different from the previous years, with 60 multiple choice questions (now with only four answer choices per question), 3 long free response questions, and 4 short free response questions.

  6. Chemistry - Wikipedia

    en.wikipedia.org/wiki/Chemistry

    Chemistry is the scientific study of the properties and behavior of matter. [1] It is a physical science within the natural sciences that studies the chemical elements that make up matter and compounds made of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during reactions with other substances.

  7. Tetradentate ligand - Wikipedia

    en.wikipedia.org/wiki/Tetradentate_ligand

    1,4,8,11-tetraazacyclotetradecane cyclam (NHCH 2 CH 2 NHCH 2 CH 2 CH 2) 2: ring NNNN 200.33 transition metals: 1,4,7,10-tetraazacyclododecane cyclen: ring N 4: 172.271 Zn Dibenzotetramethyltetraaza[14]annulene [10] tmtaa ring NNNN 2- UO 2: N,N-ethylenediaminediacetic acid NH 2 C 2 H 4 N(CH 2 COOH) 2: tripodal NNO 2: 2– N,N ...

  8. Substitution reaction - Wikipedia

    en.wikipedia.org/wiki/Substitution_reaction

    The two reactions are named according tho their rate law, with S N 1 having a first-order rate law, and S N 2 having a second-order. [2] S N 1 reaction mechanism occurring through two steps. The S N 1 mechanism has two steps. In the first step, the leaving group departs, forming a carbocation (C +). In the second step, the nucleophilic reagent ...

  9. Transition metal chloride complex - Wikipedia

    en.wikipedia.org/wiki/Transition_metal_chloride...

    The class of complexes is extensive. [1] Bonding. Halides are X-type ligands in coordination chemistry. They are both σ- and π-donors. ... H 2 N + (CH 2 CH 2 NH 3 ...