か, も, and でも as question word modifiers

Besides marking questions, か can also be used to turn question words into generic nouns.

Often なにか is slurred as なんか:

なんか飲む？
Do you want something to drink?

Make sure to not confuse the following two usages:

何があった？  
What happened? (lit. What was there?)

何かあった？  
Did something happen? (lit. Was something there?)

Note how with question words + か it is common to drop the が particle after them (何かが -> 何か), possibly because it is easier to pronounce.

In a similar manner, we can also use も to turn question words into "inclusive/exclusive" nouns. Think about words like “anything” or “nothing” in English.

ここは何もない  
There is nothing here

誰も知ってること  
Things that everyone/anyone knows.

いつもそんなことを考えてるの？  
Have you always been thinking about that?

There's a logical distinction between "every particular thing" and "any one particular thing". By attaching でも to some of these words, you can give them the "any" sense of "any one particular thing".

あんたは誰でも助けるの？  
Would you (really) save anyone (no matter who)?

場所はどこでもいい。  
Anywhere (no matter where) is fine