Is there any mistake in this sentence? Please tell
He hanged his head in shame (a)/when he came (b)/to know of his (c) son's failure. (d)/ No error (e)

Question

Answer

He hung his head in shame when he learned about his son's failure.

Answer

Using your words, you can say:

‘He hung his head in shame when he came to know of his son’s failure.’

The only change needed is for ‘hanged.’

Answer

To hang is an unusual verb because it has two past participles, the irregular 'hung' and the regular 'hanged', 'hung' can always be used but 'hanged' is an alternative if referring to an execution. So in your sentence you should choose 'hung'.