Which one of the following statements is not correct?

Statement (1) is incorrect because the largest Buddhist monastery in India is at Tawang in Arunachal Pradesh, not Assam; official sources describe Tawang Monastery as the largest monastery in India [1]. Statement (2) is correct: the Konyak (Konyaks) are listed among the tribes of Nagaland, indicating the Konyak language/community belongs to Nagaland [2]. Statement (3) is correct: Majuli in Assam is widely described as the world’s largest river island. Statement (4) is also correct: Sikkim is the least-populated among the Indian states (though several union territories have smaller populations). Therefore option (1) is the false statement.

Sources

1. [1] https://www.incredibleindia.gov.in/en/arunachal-pradesh/tawang/tawang-monastery
2. [2] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 13: Cultural Setting > 1. North East India > p. 25