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Nuclear fusion & fission reactions (HL) answers
1. (a) Mass = (92 x 1.672622.10−27) + (143 x 1.674927.10−27) kg = (153.881224 + 239.514561) x 10-27 = 3.933958 x 10-25 kg (b) Mass of one mole of U-235 nuclei = (3.933958 x 10-25) x (6.022142 x 1023)...
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Proteins & enzymes (HL) answers
1. (a) Enzymes provide an alternative pathway for the biological reaction with lower activation energy. They possess an active site where the substrate is able to bind to the enzyme. This site either...
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Introduction to biochemistry questions
1. (a) Photosynthesis describes the process used by plants to synthesise energy-rich molecules such as carbohydrates from carbon dioxide and water using visible light. (i) State the summary equation for...
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Environmental impact - heavy metals questions
1. Lead(II) ions can be removed from polluted water by precipitating them as lead(II) carbonate.The Ksp value for lead(II) carbonate is 7.40 x 10−14 at 298 K. (a) Determine the concentration of lead(II)...
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Five things everyone should know about science Free
Congratulations to Professor Gregg Semenza of John Hopkins University who was one of three people to be awarded the 2019 Nobel Prize in Physiology or Medicine in Stockholm yesterday. The prize was awarded...
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Superconducting metals & X-ray crystallography questions
(b) The diagram below shows representations of three different types of cubic cells labelled I, II and III. Identify each of the three types of cubic cell and deduce the number of atoms in each type...
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Sales of Zantac® suspended Free
Zantac is one of the most widely used H2 receptor blocker antacids A few weeks ago I wrote about the dangers of taking PPIs long term, now it is H2 receptor blockers that are coming under the spotlight....
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The danger of prolonged use of proton pump inhibitors Free
Students studying the medicinal chemistry option need to be able to explain the three main ways in which excess stomach acid can be controlled (D.4 pH regulation of the stomach). The first way is straightforward...
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104Ku - an anachronism in a gulag Free
I was reading an article recently on Dark Tourism which describes a visit in 2017 to Karlag, a former Soviet gulag near Karaganda in Kazakhstan. I visited this gulag two years earlier in 2015 and the...
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Reducing global warming by increasing CO2 concentration in the atmosphere Free
Option C (sub-topic C.5 Environmental impact – global warming) covers the science behind global warming and relates the concentrations of different greenhouse gases in the atmosphere with their global...