Are these examples correct?
He was so weak nevertheless completed the task?
The task was hard to complete but he is the man who nonetheless did that hard task.
My question is,
Are these words used as a replacement of the phrase "in spite of"?
Are these examples correct?
He was so weak nevertheless completed the task?
The task was hard to complete but he is the man who nonetheless did that hard task.
My question is,
Are these words used as a replacement of the phrase "in spite of"?
No, neither one is correct English. The first one doesn't mean anything, though the second one can be understood. However, none of the mistakes have to do with none/nevertheless, which is used correctly as an adverb in both examples.
The answer to the question
Are these words used as a replacement of the phrase in spite of?
is No. They mean roughly the same thing as that phrase, but they are not replacements for it.
Nonetheless and nevertheless (which mean the same, incidentally) are always adverbs,
and may appear in many adverb niches:
Whereas in spite of (equivalent to despite, which falutes slightly higher) is a preposition,
and must appear with a noun phrase object.
The entire prepositional phrase itself (including the object noun phrase) is a sentence adverbial,
and so it can be niched like an adverb
But in spite of by itself can't be used as an adverb: