Answer:
See explanation
Step-by-step explanation:
The addition of an impurity lowers the melting point of a solid. If we add salt to ice, the melting point of the ice is lowered.
As this salty water is in contact with the ice, more of the salt dissolves to yield Na^+ and Cl^- and leads to the melting of more ice.
Freezing point is a colligative property hence it is affected by the presence of impurities. Hence, the addition of NaCl causes ice to melt faster.