Service tax on service to govt org for medical college and h

Can anybody tell me,

cASE:- if “X” is private limited company (Sub Service Contractor) and Providing Construction quality Consultancy Services to “Y” (Service Contractor) which is a government institution and “Y” is raising bills on “A’ who is a state Government for providing construction quality consultancy service ("A" is constructing medical college and hospital).  

My Question is 1) is service tax applicable in this case? 2) is service tax applicable between “A” And “Y” 3) is service tax applicable between “Y” and “X”.

regards,

Amol Joshi