Google made it easier than ever to have quizzes scored for you and to show students their scores. Now when you create a Google Form you can go into the Form settings and choose the quiz option. Within the quiz option you can choose to have your questions scored as students answer them. You can also choose to show students their scores as well as correct answers.
http://www.freetech4teachers.com/2016/06/google-forms-can-now-automatically.html