What effect does the addition of impurities have on the melting point?

The addition of impurities typically decreases the melting point of a substance. When impurities are introduced into a pure substance, they disrupt the regular arrangement of particles within the crystal lattice. As a result, the cohesive forces between the particles are weakened, requiring less energy to overcome them and transition into the liquid phase. Consequently, the melting point of the impure substance is lower than that of the pure substance. This phenomenon is known as freezing-point depression. Therefore, the answer is [A] decrease.
It’s a common occurrence observed in everyday life, such as adding salt to ice to lower its melting point, facilitating the melting of ice on roads during winter. Therefore, the correct answer is option [A] decrease. Options [B] increase, [C] remain unchanged, and [D] None of these do not accurately describe the effect of impurities on the melting point.