The results of a titration experiment are shown in the graph below.

Using the graph, give the pH of the acid at the start of the titration, before any sodium hydroxide solution was added.
Practise Edexcel GCSE Chemistry Acids with exam-style questions for Foundation and Higher tier. 100 questions, matched to the Edexcel GCSE Chemistry (1CH0) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.