unanswered vs uncertain

unanswered

adj
  • That has not been answered or addressed. 

uncertain

adj
  • Not known for certain; questionable. 

  • Not certain; unsure. 

  • Not yet determined; undecided. 

  • Variable and subject to change. 

  • Fitful or unsteady. 

  • Unpredictable or capricious. 

noun
  • Something uncertain. 

How often have the words unanswered and uncertain occurred in a corpus of books? (source: Google Ngram Viewer )