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How do I know if an enthalpy change should be positive or negative?

A negative enthalpy change represents an exothermic change where energy is released from the reaction, a positive enthalpy change represents an endothermic reaction where energy is taken in from the surround...
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Answered by Alex S. • Chemistry tutor
94949 Views

What are the two different types of circular flow of income models?

The first is in a closed economy, where there are just households and firms present and thus no exchange between the two in terms of spending and transfer of goods and services. The second is in an open econ...
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Answered by Rohan T. • Economics tutor
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Gas exchange happens in the alveoli of the lungs. What are three adaptations of the alveoli that allow for this?

Thin alveolar walls for O2 and CO2 to travel through - To travel across the membrane, gases have to be dissolved, so the alveolar walls are moist - Large surface area to volume ratio allows for maximum gas e...
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Answered by Sarah L. • Biology tutor
3785 Views

I don't know how to select quotes from the book to use in an essay/exam

Rather than aimlessly searching through a novel looking for a quote, it is far easier to have a bank of quotes that you know well and can analyse, which can be applied to a variety of questions. To make sure...
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Rearrange to make x the subject of the equation: 4(3x+y) = 12-2y

To tackle this question, start by expanding the brackets: 12x + 4y = 12 - 2y Making x the subject of the equation requires x to be on its own. So, in this example, we need to first get rid of the 4y. Given t...
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Answered by Mana R. • Maths tutor
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