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How do I get those top grades in English? As and A*s?

The difference between English GCSE and English at A level is the volume of independent learning. This means taking an active approach to your essays and further reading surrounding the texts at A level. ...

Answered by Sophie F. • English Literature tutor

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How do you prove by contradiction the irrationality of surds. Use sqrt 2 as an example.

Proof by contradiction works by working of the assumption a statement is true, then showing it contradicts with a known truth. It's easy to rote learn the main ones required for Maths A Levels (irriationa...

Answered by • Maths tutor

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Why would a patient with no helper T cells not produce any antibodies?

This is because helper T cells are required to cause the proliferation of plasma B cells that produce antibodies once they recognise the antigen on an antigen presenting cell as harmful.

Answered by • Human Biology tutor

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Explain the concept of collective responsibility in relation to the UK cabinet

Collective responsibility is the concept that members of the cabinet cannot pubically disagree with the decisions of the cabinet and must agree and support any decisions made.

Answered by • Government and Politics tutor

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A buffer solution was formed by mixing 20.0 cm^3 of sodium hydroxide solution of concentration 0.100 mol dm^–3 with 25.0 cm^3 of ethanoic acid of concentration 0.150 mol dm^–3. CH3COOH + NaOH---CH3COONa + H2O Calculate the pH of this buffer solution.

Ka for ethanoic acid = 1.74 × 10–5 mol dm^–3 also given in question. moles = concentration x volume / 1000Ka = [H+] [A-]/[HA]pH = -log [H+]
initial moles:NaOH: 20x0.1/1000 = 0.002molCH_...

Answered by • Chemistry tutor

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