The Irony and the pun in the sentences are as follows:
1. Ned said, I just love working in the hot sun. When can we do this again?"
The above sentence shows irony ,as no one would want to work in the hot sun, but Ned is expressing contrary to it.
2. Billy Fisher was a minor character and remained one as an adult
The above phrase show a play with words and also depicts dark humor, as it suggests the Billy would be a minor, even as an adult. Thus this suggests pun in the sentence.
3. Kara read that Tom Sawyer tricked the boys. What a good friend!" she remarked.
This sentence shows irony, as what is being exclaimed by Kara is the opposite to what Tom's deed are.
4.His friend's none the wiser, Tom surveyed the results of his whitewashing.
This sentence suggests neither irony, nor pun.
