The prefix for "dismayed" is "dis-." This prefix is used to indicate a negation or reversal of the state described by the root word. In this case, "dismayed" conveys a sense of being troubled or distressed, with "dis-" suggesting a departure from a state of ease or contentment.
im-
Downcast and dismayed, Danny felt quite dejected when dumped by his girlfriend.
em is the preffix of the words emessiary
YES. Their reaction dismayed him. It can also be an adjective: He was dismayed at the change in his old friend.
I think it could be a root word.
He was dismayed at the thought of not seeing them again.
The prefix of "unemotional" is "un-" and the suffix is "-al".
was dismayed to find that his partners political credit not good
No, it isn't.
Gladdened.
pleasant surprise
They were not, however, dismayed by the news. The above sentence required two commas.