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why does silicon dioxide have such a high melting/boiling point?

It has a giant lattice structure, strong covalent bonds are difficult to break etc.

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Explain the importance of the separation of powers. (4 marks)

In the UK system, a separation of powers is maintained between the Houses of Parliament, the legislative body, Government, the executive body; and the courts, the judiciary. This separation of powers is i...

Answered by George N. • Law tutor

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Tom is making gift bags, each of which will contain two balloons. He wants to hide a sweet in one of the balloons. 20 balloons cost £1.33, 15 sweets cost £2.05. What is the minimum he needs to spend to make 35 bags?

First work out how many balloons he will need to buy. In order for each bag to have two balloons, he will need 70 balloons. Since he can buy 20 balloons at a time, this implies the mi...

Answered by Peter T. • Maths tutor

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Which of these lines are parallel to y=2x+3? Which are perpendicular? Options: 1) y=5x-4, 2) y=-1/3x+3, 3) y=-1/2x-1, 4) y=2x-2/3

There are two ways of doing this question, one would be to sketch the graphs and see which are parallel to and which are perpendicular to the original line. Whilst this is valid, sketching lines isn’t alw...

Answered by Peter T. • Maths tutor

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1. X with 2,4-DNPH forms a red precipitate. 2. X reduces blue Copper ions into red precipitate. What kind of compound is X?

X with 2,4 DNPH (Brady's reagent) is used to show the presence of an aldehyde or ketone. X also reduces Copper ions (Fehling's) meaning it has to be an aldehyde and not a ketone as ketones are not readily...

Answered by Tom A. • Chemistry tutor

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