Hi Archana,
Please find below the answers to your querries in seriatim :-
1. how many people are required to go an a strike? :-The Trade union Act,1926 doesn't contain any provision fixing the minimum no. of persons, who can call for a strike ? The persons who are employed in the public utility service are not allowed to go on strike in breach of their contract.
2. how many people are required to form a trade union? :- Any seven or more members of a trade union may, by subscribing their names to the rules of the trade union and by otherwise complying with the provisions of this Act can apply for registration of the trade union.
3. where to get the trade union registered?:- The appropriate government appoints Registrar of Trade Unions for each State.In addition government appoints Additional and Deputy Registrars of Trade Unions for the purpose of exercising and discharging such powers and functions of the Registrar under this Act within their local limits.
BS Kalsi