N + NO/NA/DA + わけ and generic rule?


I found in dictionary わけ is a Noun, However, I see in the book that Noun will
go with な when using with わけ, as N な + わけがない/わけはない.

Besides わけ, is there any Japanese word that has that exception?

Why has it become like that? And there is any general rule for us to remember?
Thanks a lot.




If N is a pure noun such as 学生 or 食べ物, N **の** わけがない is the norm in formal
settings. N **な** わけがない is usually acceptable, but tends to sound colloquial.
な is sometimes used also before 理由, こと, 場合, etc. If N is a na-adjective (aka
descriptive noun) such as 簡単, simply な should be used. Nだわけがない is always
ungrammatical.

See also: [嘘なわけ in this
sentence?](https://japanese.stackexchange.com/q/58009/5010)




If N is a pure noun such as 学生 or 食べ物, N **の** わけがない is the norm in formal
settings. N **な** わけがない is usually acceptable, but tends to sound colloquial.
な is sometimes used also before 理由, こと, 場合, etc. If N is a na-adjective (aka
descriptive noun) such as 簡単, simply な should be used. Nだわけがない is always
ungrammatical.

See also: [嘘なわけ in this
sentence?](https://japanese.stackexchange.com/q/58009/5010)

