Top answers

What is empirical formula and how is it worked out?

This is the lowest/simplest ratio of the molecule. For example propene has the formula C 3 H 6 - if we look a the subscript numbers (the ones down here!) we can see that smaller numbers are possible. It is i...
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Answered by Emma W. • Chemistry tutor
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What is the difference between a scalar and a vector quantity?

A scalar quantity has magnitude only - for example distance.A vector has magnitude and direction - for example gravity (acceleration towards the centre of Earth).
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Answered by Emma W. • Physics tutor
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What is the difference between diffusion and active transport?

Diffusion is the movement of particles from a high concentration to a low concentration . This process does not require energy. An example of diffusion is oxygen moving from the airways to the lungs - there ...
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Answered by Emma W. • Biology tutor
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If 2x + y = 13 and 3x - y = 12, what are the values for x and y?

To solve these simulataneous equations we need to use substitution :If 2x + y = 13 then y = 13 - 2xTherefore 3x - y = 12 can be rewritten as 3x - (13 - 2x) = 12We can expand these brackets and solve for x :3...
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Answered by Emma W. • Maths tutor
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How do you use 90mins to write 6 short essays? It is very difficult as i always run out of time.

The best way to tackle this is to practice strictly with time before the exam. I understand your frustration with the time limit especially when you know a lot. Doing loads of essay plans is very important i...
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