Is standard deduction applicable to all the salaried person whether he is an employee of Central or State Government?

Yes, a standard deduction of Rs. 40,000/-( Rs.50,000/- from FY 2019-20) or the amount of the salary whichever is less is given to all the salaried employees including the employees of the state and central government.
It is available to all class of employees irrespective of the nature of employer.