Theory certificate is needed when you want to take your exam. It is highly advised to do the exam a few weeks before your practical exam. The reason here fore is that the certificate is valid for 1,5 year. The theory test will take about one hour.
The exam is built with 65 questions. Of these questions you should have 47 good answers . You may only enter 18 wrong answers. This is divided into two arrangements. The first part of the exam will be built up with 25 questions, for this you need 12 right answers to pass. The second part you need 35 good answers from 40 questions. Its only possible to do the theory exam if you are 16 years or older.