It is a good idea to solve the model papers to get an idea of the exam pattern, marking scheme and time management techniques. You can find the model papers for History for Bihar Board 2020 on the given link: https://school.careers360.com/download/sample-papers/bihar-board-12th-history-model-paper-2020

You can also find many sets of the subject wise model papers on the official website of BSEB. The link for the website is: http://biharboardonline.bihar.gov.in/model-question-papers-ss

You can go to the subject 'History' and click on the link to download 10 sets of question papers. All the best.