Which one among the following statements regarding the Government of India Act, 1935 is not correct?

The Government of India Act, 1935, proposed an All-India Federation comprising British Indian provinces and Princely States [1]. While joining the federation was mandatory for British provinces, it was entirely voluntary for the Princely States [2]. The federation would only be established if a sufficient number of states, representing half the total population of the states, signed the 'Instrument of Accession'. Since the required number of Princely States did not join, the federal part of the Act never came into operation [4]. Other provisions were correctly implemented: Provincial Autonomy was introduced, replacing diarchy [1]; bicameral legislatures were established in six provinces—Madras, Bombay, Bengal, United Provinces, Bihar, and Assam [4]; and communal electorates were extended to include depressed classes, women, and labor [2]. Therefore, the statement that states were compelled to enter the federation is incorrect.

Sources

1. [1] Rajiv Ahir. A Brief History of Modern India (2019 ed.). SPECTRUM. > Chapter 20: Debates on the Future Strategy after Civil Disobedience Movement > Government of India Act, 1935 > p. 410
2. [2] Rajiv Ahir. A Brief History of Modern India (2019 ed.). SPECTRUM. > Chapter 26: Constitutional, Administrative and Judicial Developments > Government of India Act, 1935 > p. 512
3. [4] https://gacbe.ac.in/pdf/ematerial/18BHI14C-U2.pdf