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  2. Strontium - Wikipedia

    en.wikipedia.org/wiki/Strontium

    Natural strontium is a mixture of four stable isotopes: 84 Sr, 86 Sr, 87 Sr, and 88 Sr. [11] On these isotopes, 88 Sr is the most abundant, makes up about 82.6% of all natural strontium, though the abundance varies due to the production of radiogenic 87 Sr as the daughter of long-lived beta-decaying 87 Rb. [22] This is the basis of rubidium ...

  3. Zintl phase - Wikipedia

    en.wikipedia.org/wiki/Zintl_phase

    There are examples of a new class of compounds that, on the basis of their chemical formulae, would appear to be Zintl phases, e.g., K 8 In 11, which is metallic and paramagnetic. Molecular orbital calculations have shown that the anion is (In 11 ) 7− and that the extra electron is distributed over the cations and, possibly, the anion ...

  4. Strontium oxide - Wikipedia

    en.wikipedia.org/wiki/Strontium_oxide

    About 8% by weight of cathode-ray tubes is strontium oxide, which has been the major use of strontium since 1970. [3] [4] Color televisions and other devices containing color cathode-ray tubes sold in the United States are required by law to use strontium in the faceplate to block X-ray emission (these X-ray emitting TVs are no longer in production).

  5. Central Board of Secondary Education - Wikipedia

    en.wikipedia.org/wiki/Central_Board_of_Secondary...

    On 12 April 2018, the police said that Rakesh Kumar, who leaked the class 12 economics paper, had leaked class 10 mathematics paper also. [40] Consequently, the Central Board of Secondary Education has put in place a system of "encrypted" question papers, which are supposed to be printed by the schools half an hour before the exam starts.

  6. List of chemistry mnemonics - Wikipedia

    en.wikipedia.org/wiki/List_of_chemistry_mnemonics

    A mnemonic is a memory aid used to improve long-term memory and make the process of consolidation easier. Many chemistry aspects, rules, names of compounds, sequences of elements, their reactivity, etc., can be easily and efficiently memorized with the help of mnemonics.

  7. Chemical reaction - Wikipedia

    en.wikipedia.org/wiki/Chemical_reaction

    Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur. The substance (or substances) initially involved in a chemical reaction are called reactants or reagents.

  8. Strontium nitride - Wikipedia

    en.wikipedia.org/wiki/Strontium_nitride

    Strontium nitride, Sr 3 N 2, is produced by burning strontium metal in air (resulting in a mixture with strontium oxide) or in nitrogen. Like other metal nitrides, it reacts with water to give strontium hydroxide and ammonia: Sr 3 N 2 + 6 H 2 O → 3 Sr(OH) 2 + 2 NH 3

  9. Thermochemistry - Wikipedia

    en.wikipedia.org/wiki/Thermochemistry

    A reaction may release or absorb energy, and a phase change may do the same. Thermochemistry focuses on the energy exchange between a system and its surroundings in the form of heat. Thermochemistry is useful in predicting reactant and product quantities throughout the course of a given reaction.

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    class 12 english notes sr zone of change chemistry free download