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Why is Lithium a +1 ion and Chlorine a -1 ion?

The answer lies in how many electron there are in the outer shells of each of the elements and how many electrons they can get or give away to gain a fuller outer shell. Lithium has 1 electron in its outer s...
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A triangle has sides of 4cm and 5cm with the hypotenuse unknown. What is the length of the unknown side?

Pythagorus' theorem a^2 + b^2 = c^2 4^2 + 5^2 = c^216+25 = c^241 = c^2Root 41 or 6.403 = c
Answered by • Maths tutor
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A teacher gives her students a maths test and they receive the scores: 4, 4, 7, 3, 9, 10, 5, 8. What was the mean score of the class?

To work out the mean, we first add up all of the scores so 4+4+7+3+9+10+5+8= 50. We then divide by the number of student who took the test, or the number of scores given, which is 8. Divide 50 by 8 to give u...
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Answered by Carmen L. • Maths tutor
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Solve x^2+6x+5=0

Use factorisation to solve this. You must find a pair of numbers that add to make 6 and multiply to make 5. In this question, 5 and 1 add to make 6 and they also multiply to make 5. So the factorised equatio...
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Answered by Carmen L. • Maths tutor
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5.00 g of copper(II) carbonate decomposes to form copper(II) oxide and carbon dioxide: CuCO3(g) → CuO(s) + CO2(g). Calculate the maximum mass of carbon dioxide that can be produced. (Mr of CuCO3 = 123.5, Mr of CO2 = 44.0)

Moles of CuCO3 (using triangle) = 5.00/123.5 = 0.0450 mol.1 mol of CuCO3 makes 1 mol of CO2, therefore 0.0450 mol of CuCO3 makes 0.0450 mol of CO2.Using the triangle, mass of CO2 = 44 x 0.0450 = 1.78 grams
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Answered by Clemmie B. • Chemistry tutor
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