Question

effect of impurities on melting point ..plz don't give answer from gogle because I had already gone through it

Answer 1

The melting point decreases.

For example consider a compound FeCl2 .
Now let there melting point be m and crystal lattice energy be x .

FeCl2 is the energy released when Fe and Cl combine . But on adding the impurities the crystal lattice energy decreases{<x} thus force of attraction also decreases , hence melting point decreases{<m}