The police received a call about the attack around 10 am. The woman was rushed to the hospital.
The accused, Ravi Kumar, 23, later surrendered at the local police station and admitted to have thrown diluted acid (toilet cleaner) on her.
"He was suspicious that she was talking to some other boy. The girl has been admitted to AIIMS with some burn injuries on her body," a senior police officer said.
The police said the victim's marriage had been fixed and she was avoiding Ravi which instigated him to commit the crime.
(With inputs from agencies)