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| Q. |
Water is not effective in extinguishing a fire caused by petrol because – |
| A. | the flame is too hot for water to cool it down |
| B. | water and petrol react chemically |
| C. | water and petrol are miscible with each other |
| D. | water and petrol are immiscible with each other and petrol which forms the upper layer continues to burn |
| Answer» D. water and petrol are immiscible with each other and petrol which forms the upper layer continues to burn | |
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Explanation: Water is not effective in extinguishing a fire caused by petrol because water and petrol are immiscible with each other and petrol which forms the upper layer continues to burn. The specific gravity (or relative density) of gasoline ranges from 0.71-0.77 kg/l (719.7 kg/m3) while the specific gravity of water is 1000 kg/m3 and that is why gasoline or petrol floats on the upper surface of the water. Water cannot generally be used to extinguish a gasoline fire, unless used in a fine mist. |
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