Legal provisions for mandatory referendums at national level

India
Answer
No
Source
No provisions found on direct democrcay in India
India's Constitution of 1949 withAmendments through 2012
https://www.constituteproject.org/constitution/India_2012.pdf
Direct Democracy in Asia: A Reference Guide to the Legislation and Practice (2005), page 124 on India.
http://www.docstoc.com/docs/74258274/Direct-Democracy-in-Asia