**Water is used as coolant in automobile radiators because of its high specific heat capacity.**

**Explanation:**

Water is the most commonly used coolant in automobile radiators due to several reasons, one of which is its high specific heat capacity. Here's a detailed explanation of why water is an ideal coolant:

1. **Specific Heat Capacity:** Water has a high specific heat capacity, which means it can absorb and store a significant amount of heat energy without a significant rise in temperature. This property allows water to effectively absorb heat from the engine and prevent overheating. Compared to other substances, water requires more energy to raise its temperature, making it an efficient coolant.

2. **Heat Transfer:** Water has excellent heat transfer properties. It can easily transfer heat from the engine to the radiator, where it can be dissipated into the surrounding air. This efficient heat transfer helps in maintaining the engine temperature within the desired operating range.

3. **Availability:** Water is readily available and easily accessible. It can be sourced from various natural sources or treated for use in automobile radiators. This makes it a cost-effective coolant option compared to other specialized coolant alternatives.

4. **Safety:** Water is non-toxic, non-corrosive, and environmentally friendly. It does not pose any significant health hazards if it leaks or comes into contact with the engine components. In case of any leaks, water can be easily replenished without causing any harm.

5. **Compatibility:** Water is compatible with most engine materials, including aluminum, copper, and steel. It does not cause any adverse chemical reactions or corrosion, ensuring the longevity of the engine and radiator components.

6. **Regulation:** Water as a coolant is well-regulated and meets the required standards for automotive applications. Its properties and performance have been extensively studied and tested, ensuring its suitability for use in automobile radiators.

In conclusion, water is used as a coolant in automobile radiators primarily due to its high specific heat capacity, efficient heat transfer properties, availability, safety, compatibility with engine materials, and regulatory compliance. These factors make water an ideal coolant option for maintaining optimal engine temperature and preventing overheating.

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