What is added to water in cold countries in the radiators of cars during winters to reduce its freezing point?

Ethylene glycol

The answer is Ethylene glycol.

Ethylene glycol is a clear, colorless, and odorless liquid that is added to water in the radiators of cars during winters to reduce its freezing point. Ethylene glycol lowers the freezing point of water by lowering the intermolecular forces between the water molecules. This allows the water to remain liquid at a lower temperature, which helps to prevent the engine from freezing.

Benzene, alum solution, and NaCl do not lower the freezing point of water as effectively as ethylene glycol. In fact, NaCl can actually increase the freezing point of water.

Here are some additional details about ethylene glycol:

• Ethylene glycol is also used as an antifreeze in other applications, such as in windshield washer fluid and in some types of batteries.
• Ethylene glycol is a toxic substance, so it is important to handle it with care.
• Ethylene glycol is flammable, so it is important to keep it away from open flames.