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Date November Example question Marks available 2 Reference code EXN.1.SL.TZ0.5
Level Standard Level Paper Paper 1 Time zone Time zone 0
Command term Find Question number 5 Adapted from N/A

Question

The pH of a solution is given by the formula pH=log10C where C is the hydrogen ion concentration in a solution, measured in moles per litre (Ml-1).

Find the pH value for a solution in which the hydrogen ion concentration is 5.2×108.

[2]
a.

Write an expression for C in terms of pH.

[2]
b.i.

Find the hydrogen ion concentration in a solution with pH 4.2. Give your answer in the form a×10k where 1a<10 and k is an integer.

[2]
b.ii.

Markscheme

* This sample question was produced by experienced DP mathematics senior examiners to aid teachers in preparing for external assessment in the new MAA course. There may be minor differences in formatting compared to formal exam papers.

pH=-log105.2×10-8=7.29 7.28399        (M1)A1

 

[2 marks]

a.

C=10pH     (M1)A1

 

Note: Award M1 for an exponential equation with 10 as the base.

 

[2 marks]

b.i.

C=104.2=6.30957×105   (M1)

6.31×10-5        A1

 

[2 marks]

b.ii.

Examiners report

[N/A]
a.
[N/A]
b.i.
[N/A]
b.ii.

Syllabus sections

Topic 1—Number and algebra » SL 1.1—Using standard form
Topic 1—Number and algebra » SL 1.5—Intro to logs
Topic 1—Number and algebra

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