Explanation:

Single Citizenship:

• Though the Indian Constitution is federal and envisages a dual polity (Centre and states), it provides for only a single citizenship, that is, the Indian citizenship. The citizens in India owe allegiance only to the Union.There is no separate state citizenship. The other federal states like USA and Switzerland, on the other hand, adopted the system of double citizenship.
• In USA, each person is not only a citizen of USA but also of the particular state to which he belongs. Thus, he owes allegiance to both and enjoys dual sets of rights–one set conferred by the national government and another by the state government.
• This system creates the problem of discrimination, that is, a state may discriminate in favour of its citizens in matters like right to vote, right to hold public offi ces, right to practice professions and so on. This problem is avoided in the system of single citizenship prevalent in India.