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In chemistry a donor number (DN) is a quantitative measure of Lewis basicity.A donor number is defined as the negative enthalpy value for the 1:1 adduct formation between a Lewis base and the standard Lewis acid SbCl 5 (antimony pentachloride), in dilute solution in the noncoordinating solvent 1,2-dichloroethane with a zero DN.
Serial sevens (or, more generally, the descending subtraction task; DST), where a patient counts down from one hundred by sevens, is a clinical test used to test cognition; for example, to help assess mental status after possible head injury, in suspected cases of dementia or to show sleep inertia.
Mental calculation often involves the use of specific techniques devised for specific types of problems. People with unusually high ability to perform mental calculations are called mental calculators or lightning calculators. Many of these techniques take advantage of or rely on the decimal numeral system.
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.
Wechsler believed that "mental age norms clearly did not apply to adults." [6] Wechsler criticized the then existing Binet scale because "it did not consider that intellectual performance could deteriorate as a person grew older." [6] These criticisms of the 1937 Binet test helped produce the Wechsler–Bellevue scale, released in 1939.
In chemistry, the term "turnover number" has two distinct meanings. In enzymology , the turnover number ( k cat ) is defined as the limiting number of chemical conversions of substrate molecules per second that a single active site will execute for a given enzyme concentration [ E T ] for enzymes with two or more active sites. [ 1 ]
In Zimbabwe, where clinical mental health services are scarce, her chances of getting professional help were next to zero. A wooden bench and an empathetic grandmother saved her.
A mental calculator or human calculator is a person with a prodigious ability in some area of mental calculation (such as adding, subtracting, multiplying or dividing large numbers). In 2005, a group of researchers led by Michael W. O'Boyle, an American psychologist previously working in Australia and now at Texas Tech University , has used MRI ...