（疑問詞）〜か ka
（疑問詞）〜か（ka）means “embedded question (whether / what / who…)”. A question that contains a question word (なに, だれ, いつ, どこ…) can be embedded inside a larger sentence by ending the clause with か. Formation: 疑問詞＋V/Aい（普通形）＋か／ナA・N（普通形、だ脱落）＋か
embedded question (whether / what / who…)
N4Formation
疑問詞＋V/Aい（普通形）＋か／ナA・N（普通形、だ脱落）＋か
Explanation
A question that contains a question word (なに, だれ, いつ, どこ…) can be embedded inside a larger sentence by ending the clause with か. The whole clause then works as the object of verbs like 知る, 分かる, 聞く, 教える. With な-adjectives and nouns the plain だ is dropped before か (きれいか, がくせいか).
Examples
Note
When there is no question word (yes/no question), use 〜かどうか instead, e.g. くるかどうか (whether or not (someone) comes).
FAQ
（疑問詞）〜か — what does it mean and how is it used?
embedded question (whether / what / who…). A question that contains a question word (なに, だれ, いつ, どこ…) can be embedded inside a larger sentence by ending the clause with か. The whole clause then works as the object of verbs like 知る, 分かる, 聞く, 教える. With な-adjectives and nouns the plain だ is dropped before か (きれいか, がくせいか).
（疑問詞）〜か — how do you form it?
疑問詞＋V/Aい（普通形）＋か／ナA・N（普通形、だ脱落）＋か
（疑問詞）〜か — any usage notes?
When there is no question word (yes/no question), use 〜かどうか instead, e.g. くるかどうか (whether or not (someone) comes).