Q:

When using ka, is it acceptable to eliminate the question mark when ending a sentence?

I am unable to find content addressing this question.

A:

For writing in Japanese, question marks after か appear to be less common than simple periods in plain-text formats like novels.  For manga, question marks seem to be more common.  For writing in romaji, question marks appear to be standard.
Note that this is all from my own subjective perspective.

