Question 43

Salt lowers the temperature at which ice melts.

Applying salt to icy roadways is effective because it lowers the freezing point of water, which helps to melt the ice.

A) dissolves ice

While salt does dissolve in water, this option is misleading in the context of ice on roadways. Salt does not directly dissolve the ice; rather, it alters the melting point of the ice, making it more effective in preventing ice formation.

B) lowers the temperature at which ice melts

This option is correct as salt decreases the freezing point of water. When salt is spread on icy roads, it disrupts the equilibrium of the ice, causing it to melt even at temperatures below 0°C (32°F), thereby improving safety on roadways.

C) increases the temperature of the ice

This option is incorrect because salt does not increase the temperature of the ice. Instead, it changes the melting properties of ice without raising its temperature, allowing it to remain liquid at lower temperatures.

D) decomposes water

This option is also incorrect as salt does not decompose water. In fact, salt remains intact as it interacts with water, enhancing its melting properties rather than affecting the water itself.

Conclusion

The correct answer is B, as it accurately describes the mechanism by which salt is used to manage icy road conditions. The other options fail to capture the essential role of salt in altering the melting point of ice and do not provide a valid explanation for its application in winter roadway maintenance.