He was ironing when the phone rang.
Answer : Absent minded is a state of mind where a person is not attentive to the present situation (or what is happening around) rather is lost in thinking other things in mind. In this case when the professor was ironing his clothes, he was lost in thoughts and was absent minded while performing the task of ironing. When he got a phone call on his mobile which was besides iron, he picked up the iron and touched it near his ear; which burnt his ear as iron was steaming hot.
Absent minded means inattentive because of rationally
thinking about other things what a person is actually doing. A person tends to
lack attention in what they are doing. The professor probably burn his ear when
he was ironing when his phone rang.