It is an unfair labor practice for an employer to:
(1) Interfere with, restrain, or coerce employees in the exercise of their rights guaranteed by this chapter;
(2) Control, dominate, or interfere with a bargaining representative;
(3) Engage in or create the impression of surveillance of activities protected by this chapter;
(4) Discriminate against an employee who has filed an unfair labor practice charge or who has given testimony under this chapter; or
(5) Refuse to engage in collective bargaining.