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How does a vaccination work?

To start we need to ask: what causes an infection? The answer is a pathogen, which is a microbe that causes disease. These can be bacteria or viruses. A vaccine contains dead or inactive pathogens that are i...
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Answered by Jessica S. • Biology tutor
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An equation for the reaction is: NiO + C = Ni + CO Calculate the percentage atom economy for the reaction to produce nickel. Relative atomic masses (Ar): C = 12 Ni = 59 Relative formula mass (Mr): NiO = 75 Give your answer to 3 significant figures.

Atom economy is a percentage value which tells you how efficient the product is in comparison to the amount of reactant used.Equation to learn: atom economy = Ar of useful product/Ar of reactant Substitute t...
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Donnez-moi une brève description de vos dernières vacances d’été et ce que vous avez fait

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Answered by Ollie J. • French tutor
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S is a geometric sequence. a) Given that (√x - 1), 1, and (√x + 1) are the first three terms of S, find the value of x. b) Show that the 5th term of S is 7 + 5√2

a) We can get the result by calculating the common ratio between elements 1 and 2, and 2 and 3. R n = 1/√x-1 /Ratio between 1st and 2nd R n = √x + 1 /Ratio between 2nd and 3rd 1/√x-1 = √x + 1 /*(x + 1) 1 = (...
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Answered by Marek D. • Maths tutor
12467 Views

Evaluate one reason why trade may be beneficial for an economy (5 marks)

Trade is the international exchange of goods and services. An economy can engage in trade because of the variation of production efficiency between countries, it is able to export goods it produces at a rela...
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Answered by Ankit M. • Economics tutor
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