Where is the India’s first liquid mirror telescope established ?

Ramgarh
Hartola
Devasthal
Patwadangar

The correct answer is (c) Devasthal.

Devasthal is an astronomical observatory located in Nainital district of Uttarakhand, India. It is the site of India’s first liquid mirror telescope, the 3.6-meter Devasthal Optical Telescope (DOT). The DOT is the largest liquid mirror telescope in the world. It was inaugurated in 2012 and is used for astronomical research in the fields of exoplanets, star formation, and dark matter.

The other options are incorrect. Ramgarh is a town in Jharkhand, India. Hartola is a village in Uttar Pradesh, India. Patwadangar is a hill station in Maharashtra, India.