Hello Dear,

National Means cum Merit Scholarship Scheme Exam is conducted every year by Science Branch of Directorate of Education, Delhi usually in the month of November for the students studying in class VIII of Govt./Aided schools.  You can refer to the following link and check the article that provides you the link of all the previous yer question papers with answer keys till 2020-

https://school.careers360.com/articles/nmms-question-papers

Good Luck