All examinations shall be impartial, fair, and practical and designed only to test the relative qualifications and fitness of applicants to discharge the duties of the particular employment which they seek to fill. No question in any examination shall relate to the political or religious convictions or affiliations of the applicant. All applicants for positions of trust and responsibility shall be specially examined as to moral character, sobriety, and integrity, and all applicants for position requiring special experience, skill, or faithfulness shall be specially examined in respect to those qualities. It shall be the duty of the chief of the police department and of every employee to act as an examiner or assistant examiner, at the request of the commission, without special compensation therefor. The members of the commission collectively or individually may act as examiners or assistant examiners.