Search results
Results from the WOW.Com Content Network
The only stable chalcogenides under normal conditions are aluminium sulfide (Al 2 S 3), selenide (Al 2 Se 3), and telluride (Al 2 Te 3). All three are prepared by direct reaction of their elements at about 1,000 °C (1,832 °F) and quickly hydrolyse completely in water to yield aluminium hydroxide and the respective hydrogen chalcogenide .
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.
Also acid ionization constant or acidity constant. A quantitative measure of the strength of an acid in solution expressed as an equilibrium constant for a chemical dissociation reaction in the context of acid-base reactions. It is often given as its base-10 cologarithm, p K a. acid–base extraction A chemical reaction in which chemical species are separated from other acids and bases. acid ...
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. This article contains the list of certain mnemonics in chemistry.
While the term chemical substance is a precise technical term that is synonymous with chemical for chemists, the word chemical is used in general usage to refer to both (pure) chemical substances and mixtures (often called compounds), [14] and especially when produced or purified in a laboratory or an industrial process.
A number of subjects: English Language, English Literature, Bahasa Melayu (Malay language), Malay Literature, Islamic Religious Knowledge, Ulum al-Quran, Hafaz al-Quran, Tafsir al-Quran (Asas), History, Geography, Pure sciences (Physics, Chemistry and Biology), Arabic, Art and Design offer exam papers and syllabuses unique to Brunei.
Windows: Windows 7 and newer Mac: MacOS X and newer Note: Ad-Free AOL Mail removes ads while using AOL email; it is not supported on AOL Desktop Gold or the AOL mobile app.
26 Al was present in the early Solar System with abundance of 0.005% relative to 27 Al but its half-life of 728,000 years is too short for any original nuclei to survive; 26 Al is therefore extinct. [63] Unlike for 27 Al, hydrogen burning is the primary source of 26 Al, with the nuclide emerging after a nucleus of 25 Mg catches a