Is this an appropriate way to present the Back and Next buttons in the Android application?

As part of a test application, in which users have to go through a set of questions, I must provide the ability to:

  1. Leave the questionnaire
  2. Go to the next question
  3. Go (back) to the previous question

I am trying to implement some design principles of materials in my design. Is this a legitimate way to do this: have the Back and Next buttons on the bottom bar? Please advise.

see screenshot