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Calculate the threshold wavelength for a metal surface with work function of 6.2 eV.

threshold wavelength where photoelectrons have no energy, i.e. Work function = hc/wavelength.Rearrange for wavelength and substitute. Wavelength = 2*10^-7 m.
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Answered by Daniel P. • Physics tutor
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Outline the action of B lymphocytes following initial contact with an antigen or antigen presenting cell. (6 marks)

There are 4 stages to the response of B lymphocytes upon contact with antigens. These are antigen presentation, clonal selection, clonal expansion and differentiation. During antigen presentation the lymphoc...
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Answered by Amy D. • Biology tutor
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Write an equation for the incomplete combustion of dodecane to produce gaseous products only.

C10H22 (l) + 11.5O2 (g) --> 10CO(g) + 11H20 (g)Incomplete combustion so the products are CO and H2O, remember to include state symbols as the question asks for gaseous products.
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Answered by Fawcett G. • Chemistry tutor
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Describe the process of diffusion?

Diffusion is the process where water molecules move from a negative water potential to a more negative water potential through a semi permeable membrane.
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Answered by Fawcett G. • Biology tutor
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Solve the simultaneous equations 4x + 5y = 13 and 3x - 2y = 27.

Using the elimination method to remove the variable x, we need both equations to have the same values of x. To do this we find the lowest common multiple of the x values: the lowest common multiple of 3 and ...
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Answered by Christy H. • Maths tutor
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