Explanation:

1 only

The statement "In both these cases, Parliament can make laws on the subjects mentioned in the State List" is correct. During a National Emergency and President's Rule in a state, Parliament gains the authority to make laws on matters listed in the State List. This allows the Union to legislate on subjects that fall under the jurisdiction of the states.

The statement "The constitution has prescribed a maximum period of operation for both beyond which they can’t be continued" is incorrect. The Constitution of India does not specify a maximum period for the operation of a National Emergency. However, the continuance of a National Emergency beyond six months requires the approval of both houses of Parliament. President's Rule in a state, on the other hand, is subject to a maximum period of six months, after which it can be extended for up to three years with the approval of Parliament, subject to periodic reviews.

The statement "The Lok Sabha has the power to revoke both types of emergencies" is incorrect. The revocation of a National Emergency can be initiated by the President, and it does not require the approval of the Lok Sabha. Similarly, the revocation of President's Rule in a state is not solely within the jurisdiction of the Lok Sabha; it can be revoked by the President when the conditions warrant it.

Therefore, only statement 1 is correct.