At the exercise A4 on Section 19, the following three constructions are introduced;
1-1. [Subject] wa [I-adj]+ku Narimashita.
1-2. [Subject] wa [Na-adj]+ni Narimashita.
1-3. [Subject] wa [Noun]+ni Narimashita.
All three use the intransitive verb “Naru/Narimasu” in perfect tense. Note that I-adjective and Na-adjective are words that conjugate, but Noun never conjugates. Despite of the difference about conjugation, the difference exists between I-adjective and other two. I-adjective uses “ku”, but Na-adjective and Noun use “ni”.
<This is still incomplete. Give me a little time to finish this.>
This post was written with reference to the exercise A4 on Section 19 of “Minna no Nihongo (2nd Edition)” published by “3A Corporation”