Question

what did raja ram mohan roy do to oppose caste system

Answer 1

Dear Student,
According to Raja Ram Mohan Roy it was essential to liberate the Indian society from the chains of caste based customs. ​To him everybody was a son or daughter of the God, so there is no difference among men.By advocating this equality among men, Ram Mohan became the eyesore of many higher caste Indians.

Brahmo Samaj became the vehicle of Ram Mohan’s socio-religious reforms.
It saw no difference between man and man because it accepted the brotherhood of mankind.
It condemned ritualistic practices like animal sacrifice, offering of Prasad and so on. It also fought for the emancipation of women. Thus, many evil practices like caste system, sati, child marriage,polygamy etc. were the targets of the Brahmo Samaj.