A Markov chain on state space {1,2,3,4,5} has transition matrix

The process starts in state 1.c) Calculate the expectation of the time of absorption.

a) Which states are absorbing?

b) Calculate the probability that the process is absorbed at state 4 (ends up at state 4).

I am missed my lectures due illnes so I don't have much understanding of this topic. I would be grateful for some help with this revision question.

Thanks