After a brief scuffle, the teenager went back to his house only to come back with the acid and throw it on the unsuspecting Tushar, police said.
Tushar, who sustained 60% burns, was taken to the civil hospital where his condition is stated to be critical.
Superintendent of Police (Trans-Gomti) Habib-ul-Hasan said that they were probing the matter.
The attacker is yet to be apprehended.
"We are investigating the matter and action will be taken accordingly," added Hasan.
Tushar's family said that the local police initially tried to pass it off as an accident but after eye-witnesses narrated the incident and his mother protested, police said they will take action.