If someone takes a leave from Mon-Thurs is he/she eligible for taking Sunday off?

Actually, the law in most cases (factory for example), says you are eligible for paid holiday after working for 6 days.
Therefore, is an employee has worked for only 2 days in the week, he is not eligible for paid weekly off. The employer is very much entitled to deduct salary for the weekly off that comes subsequent to his working day.

In most companies, they do not bother to do it and the system automatically considers the weekly off as paid, however, I am sure the HR will take action where it is being misused.

I have a different interpretation about paid weekly off. It is true that after 6 days work (including the authorised leave days) one should get one day off or rest for 24 hours. But that need not necessarily be paid weekly off. When the Minimum wages per day is calculated by dividing the monthly wages by 26, the weekly off wages in already included in it.