なにか・だれか・どこか

 ABOUT: 

か as a sentence ender indicates a question. When added to a question or existence word, it adds uncertainty: "some …"

 Examples:

■ 何(なに)か飲(の)みたいですか？ Would you like something to drink?

■ 部屋(へや)には、誰(だれ)かいます。 Someone is in the room.

■ どこかに蚊(か)がいます。 There's a mosquito somewhere.