Vinod has been ill from Saturday. -INCORRECT
Vinod has been ill since Saturday- CORRECT
(When we talk about the specific time we use SINCE)

This bag is enough spacious for me. - INCORRECT
This bag is spacious enough for me. - CORRECT
(Whenever we use a quantifier like - ENOUGH we use it after the adjective SPACIOUS)

I have visited London last week. - INCORRECT
I visited London last week. - CORRECT
(When we use "have" in such sentences we do not specify the time.
Whenever we talk about something we did at a specific time then never use “have” in it.)

Open page 10 of your notebook. -INCORRECT
Open your notebook to page 10. -CORRECT
(The error is of the order of the words. The words are not in order in this sentence.
First, you open the book and then go to page number 10)