For the Council of Ministers to aid and advise Governor

According to Article 163 of the Indian Constitution,

1. There shall be a Council of Ministers with the Chief Minister at the head to aid and advise the Governor in the exercise of his function, except in so far as he is by or under this Constitution required to exercise his functions or any of them in his discretion.
2. If any question arises whether any matter is or is not a matter as respects which the Governor is by or under this Constitution required to act in his discretion, the decision of the Governor in his discretion shall be final, and the validity of anything done by the Governor shall not be called in question on the ground that he ought or ought not to have acted in his discretion.
3. The question whether any, and if so what, advice was tendered by Ministers to the Governor shall not be inquired into in any court.

This means that the Ministers serve under the pleasure of the Governor and he/she may remove them, on the advice of the Chief Minister, whenever they want.

For other provisions as to Ministers

According to Article 164 of the Indian Constitution,

1. The Chief Minister shall be appointed by the Governor and the other Ministers shall be appointed by the Governor on the advice of the Chief Minister, and the Minister shall hold office during the pleasure of the Governor:
   Provided that in the States of Bihar, Madhya Pradesh and Orissa, there shall be a Minister in charge of tribal welfare who may in addition be in charge of the welfare of the Scheduled Castes and backward classes or any other work.
2. The Council of Minister shall be collectively responsible to the Legislative Assembly of the State.
3. Before a Minister enters upon his office, the Governor shall administer to him the oaths of office and of secrecy according to the forms set out for the purpose in the Third Schedule.
4. A Minister who for any period of six consecutive months is not a member of the Legislature of the State shall at the expiration of that period cease to be a Minister.
5. The salaries and allowances of Ministers shall be such as the Legislature of the State may from time to time by law determine and, until the Legislature of the State so determines, shall be a specified in the Second Schedule.