Question

An impure sample of substance X melts at about 113 degress. Which of the substances could be X and state y
Resorcinal 111 degrees
Catechol 105
Nitrophenol 114
Butanamide 115

I think it is either catechol or resorcinol because as stated the higher the percentage of impurity the lower the melting point

Answer 1

I think you have the right idea but you aren't processing it correctly. It is true that the presence of an impurity makes the melting point decrease; therefore, the melting point of the impure sample must be less than the melting point of the pure sample. Doesn't that mean that the melting point of pure X must be higher than 113?