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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.
The S-level or scholarship level was a General Certificate of Education (GCE) public examination in England, Wales and Northern Ireland, taken by the most able A-level students. The 'S' level was typically used to support university entrance applications, though in practice it was directed almost exclusively to Oxbridge applications.
An image from John Dalton's A New System of Chemical Philosophy, the first modern explanation of atomic theory.. This timeline of chemistry lists important works, discoveries, ideas, inventions, and experiments that significantly changed humanity's understanding of the modern science known as chemistry, defined as the scientific study of the composition of matter and of its interactions.
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.
Version 1.06 and was released in December 2020. [8] Prior to 1.04, the software was freely available under the open-source LGPL license. [9] Versions 1.05 and 1.06 used a custom license called IUPAC-InChI Trust License. [10] The current software version is 1.07.1 (August 2024), uses the MIT license, and may be downloaded from the InChI GitHub site.
Litmus paper after being used. The main use of litmus is to test whether a solution is acidic or basic, as blue litmus paper turns red under acidic conditions, and red litmus paper turns blue under basic or alkaline conditions, with the color change occurring over the pH range 4.5–8.3 at 25 °C (77 °F). Neutral litmus paper is purple. [2]
Elephant's toothpaste is a foamy substance caused by the quick decomposition of hydrogen peroxide (H 2 O 2) using potassium iodide (KI) or yeast and warm water as a catalyst. [1] How rapidly the reaction proceeds will depend on the concentration of hydrogen peroxide.
Wikipedia trails just Yahoo, Facebook, Microsoft and Google, the largest with 1.2 billion unique visitors." [45] However, its ranking dropped to 13th globally by June 2020 due mostly to a rise in popularity of Chinese websites for online shopping. [260] The website has since recovered its ranking as of April 2022. [261]