Free Blockchain Course with Online Certification.. This exam comprises of 100 questions, 50 theory and 50 practical, to be completed within 45 minutes. The minimum passing score of the exam is above 60%. Upon passing of the exam, you will be entitled to receive a certification of competence, which will be added to the Xinfin blockchain. With the certificate on the blockchain, you will be able to check your immutable certificate using the transaction hash provided to you.