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| Q. |
Dry powder fire extinguishers contain - |
| A. | sand |
| B. | sand and sodium carbonate |
| C. | sand and potassium carbonate |
| D. | sand and sodium bicarbonate |
| Answer» D. sand and sodium bicarbonate | |
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Explanation: Dry chemical is a powder based agent that extinguishes by separating the four parts of the fire tetrahedron. It prevents the chemical reactions involving heat, fuel, and oxygen and halts the production of fire sustaining "free-radicals", thus extinguishing the fire. Sodium bicarbonate, "regular" or "ordinary" used on class B and C fires, was the first of the thy chemical agents developed. In the heat of a fire, it releases a cloud of carbon dioxide that smothers the fire. |
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