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What is a world city?

A city that has very significant economic or financial and/or political influence on an international scale. Key features:Major centre for finance, business, trade. Major centre for culture, media. Major cen...
RJ
Answered by Rose J. • Geography tutor
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How important was Ostpolitik to the reunification of Germany?

A good way to approach this question would be to break down the concepts involved. Ostpolitik can be broken down into its political, economic and social consequences, and a strong answer should differentiate...
KB
Answered by Katy B. • History tutor
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Explain how capillaries are adapted to their function of exchanging substances, giving 3 examples.

Firstly, capillaries are one cell thick and so this makes them very thin. This reduces the diffusion pathway between the capillary and other cells thus allowing efficient diffusion. Secondly, capillaries als...
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Answered by Rebecca C. • Biology tutor
20485 Views

An amino acid contains 52.2% carbon, 9.3% hydrogen, 8.7% nitrogen and 29.8% oxygen by mass and has a relative molecular mass of 161 g/mol. What is its molecular formula? What functional groups must it have?

In 100g of compound, the amount of each element is given by: C: n = 52.2/12 = 4.35 H: n = 9.3/1 = 9.3 N: n = 8.7/14 = 0.621... O: n = 29.8/16 = 1.8625 Dividing through by the smallest amount (0.621) gives: C...
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A circle with centre C has equation x^2+8x+y^2-12y=12. The points P and Q lie on the circle. The origin is the midpoint of the chord PQ. Show that PQ has length nsqrt(3) , where n is an integer.

First complete the square for both x and y. Move all constants to the right hand side. The square root of this is the radius of the circle. The two constants in the completed square bracket show the x and y ...
Answered by • Maths tutor
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