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Butane, C4H10 is burned completely in excess oxygen, write the balanced chemical formula for the reaction, name the products and type of reaction.

We need to think about the number of atoms of each element in the reactants and ensure these are the same in the products. This is the basic UNBALANCED equation. C 4 H 10 + O 2 ----> CO 2 + H 2 O So we ha...
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Answered by Callum J. • Chemistry tutor
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A cup of boiling water (100 degrees C) (0.2kg) transfers 20 000J of heat to its surrounding in 1 hour. What temperature is the water in the kettle after 1 hour?

To answer this we need to use the equation Q = MC(T1-T2) We want to know what T2 is (ie the temperature after one hour). So rearrange the equation to get T2 = T1 - Q/MC No substitute the values given: T2 = 1...
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Answered by Callum J. • Physics tutor
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How should I properly use a semi-colon?

There are many different ways in which a semicolon can be used. The first, and the most common is to link two similar clauses together. For example, you could say, 'The lady had a cat. The cat was brown', bu...
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Answered by Fern O. • English tutor
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Factorise the quadratic equation: x^2 + 5x + 6 = 0 and hence find the two solutions to the equation.

Start by writing the equation out again: x 2 + 5x + 6 = 0 I do it by thinking which two numbers add together to = 5 and which same two numbers multiply to = 6. The answer to this is 2 and 3. So the next step...
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Answered by Callum J. • Maths tutor
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i) Simplify (2 * sqrt(7))^2 ii) Find the value of ((2 * sqrt(7))^2 + 8)/(3 + sqrt(7)) in the form m + n * sqrt(7) where n and m are integers.

i) (2 sqrt(7)) 2 = 2 2 sqrt(7) 2 = 4 * 7 = 28 (1 mark) ii) First of all substitute the answer from above. ((2 * sqrt(7)) 2 + 8) / (3 + sqrt(7)) = (28 + 8) / (3 + sqrt(7)) = 36 / (3 + sqrt(7)) Multiply by (3 ...
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Answered by Andrew B. • Maths tutor
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