much marks did you is grammatically correct or not?

No, "much marks did you" is not grammatically correct. Here's why:

* "Much" is used with uncountable nouns. Marks are countable (you can have one mark, two marks, etc.).

* The sentence structure is incorrect. The correct structure would be "How many marks did you..."

Here are some ways to correct the sentence:

* "How many marks did you get?"

* "How many marks did you score?"

* "How many marks did you achieve?"