Is there any CFG available (with pos tags -part of speech tags) to validate the grammar of sentences in english?

Question

It may not be 100 % accurate but still is there any written and tested CFG. is it available with nltk data?

Answer 1

Short answer: no. Long answer: noooooooooooooo

This is a huge issue. One CFG couldn't possibly come even close to the complexity that English presents. Even the POS taggers aren't terribly accurate.

The very best spelling and grammar checkers look for invariant laws of English and violations therein. Search for English grammar rules and think about how you might use software to detect them.