Is it permissible to accept chocolate purchased based on an agreement between friends that whoever gets the highest mark in the exam buys it?

This does not fall under prohibited gambling because the one who pays the compensation is the victorious غالب, not the defeated مغلوب. Therefore, the compensation paid by the winning girl to her other friends is considered a voluntary donation and a gift. Sheikh Abd al-Rahman al-Barrak answered: "If it is in the form of a donation, there is no harm, but if it is in the form of an obligation, then it is not permissible."