Top answers

Why do ionic compounds like NaCl conduct electricity when dissolved but not when they’re solid, whereas metals conduct electricity when they’re solid?

Firstly, it's important to recognise that ionic compounds and metals are two different structures. Ionic compounds consist of positively charged ions and negatively charged ions held together by strong elect...
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Answered by Hannah B. • Chemistry tutor
42532 Views

When using cm3 as the unit for volume to calculate the concentration why must you divide the cm3 by 1000?

As I’m sure you already know, the units of concentration are mol dm -3 . So before we calculate concentrations we must convert the volume with units cm 3 to dm 3 . 1 dm is the equivalent of 10 cm . So, by cu...
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Answered by Hannah B. • Chemistry tutor
25694 Views

Solve the quadratic equation: x^2 - 2x - 15 = 0

We need to find numbers that multiply together to give -15. This could be -1 and 15, 1 and -15, -3 and 5, 3 and -5. The numbers we need must add up to -2 as well (from -2x term). Therefore our set must be 3 ...
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Answered by Sabrina K. • Maths tutor
6777 Views

Factorise completely ( x − 4x^3)

(x-4x 3 ) = x(1-4x 2 ) Just taking a factor of x out of both terms Within the inner bracket we have a difference of two squares. 1 2 =1 and (2x) 2 =4x 2 therefore we can write x(1-4x 2 ) = x(1-2x)(1+2x)
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Answered by Edward C. • Maths tutor
22717 Views

Y=3x^2-2 ( Make x the ubject of the formula

x=((y+2)/3)^1/2
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Answered by Talha P. • Maths tutor
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