Search our library of A Level questions

Top answers

All subjects

A Level

State and explain the trend in boiling points of chlorine, bromine, and iodine

Boiling point increases down the group, because of increasing strength of van der Waals (intermolecular) forces. More energy is required to break van der Waals (intermolecular) forces.Follow up questions ...

Answered by Alexander D. • Chemistry tutor

9137 Views

What is the coefficient of x^4 in the expansion of (x+3)^7

Start by expanding (a+b)⁷, using Pascal's Triangle or the binomial coefficient function to work out the coefficients:a⁷ + 7a⁶b + 21a⁵b² + 35a⁴

Answered by Josef W. • Maths tutor

8157 Views

Integrate 1/(1 - 3*x) with respect to x

First substitute: u = 1 - 3xNext calculate: du/dx = -3 .... therefore dx = (-1/3) * duNow re-arrange the expression: Integrate 1/u * ( -1/3)*duNext recall the integral of 1/x is the natural logarithm, and...

Answered by Neil M. • Maths tutor

3251 Views

How do you analyse a poem?

Writing a good, coherent poem analysis is often seen as very hard, but once you understand and have good knowledge of all the parts that make up a poem, you will see how smooth and enjoyable this process ...

Answered by Anna R. • English tutor

1669 Views