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Q26. The combustion process that takes place without any external heat is called
- Arapid combustion
- Bslow combustion
- Cspontaneous combustion
- Dexplosion
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Answer: C) spontaneous combustion
Q27. This process of combustion in which heat and light are produced in a short time is called
- Arapid combustion
- Bslow combustion
- Cspontaneous combustion
- Dexplosion
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Answer: A) rapid combustion
Q28. The explosion of a firecracker is an example of
- Aevaporation
- Bcombustion
- Cprecipitation
- Ddecomposition
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Answer: B) combustion
Q29. With what does the sodium bicarbonate solution filled in fire extinguishers react to form carbon dioxide?
- Acarbolic acid
- BGandhakaamd
- Cacetic acid
- Dnitric acid
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Answer: B) Gandhakaamd
Q30. Why is sodium bicarbonate used as a fire extinguisher?
- ABy receiving heat from the fire, it produces CO² gas.
- BIt produces CO gas by absorbing heat from the fire.
- CBy receiving heat from the fire, it produces O2 gas.
- DIt produces water by receiving heat from the fire.
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Answer: A) By receiving heat from the fire, it produces CO² gas.
Q31. Which one of the following gases is a combustion promoter?
- Ahydrogen
- Bnitrogen
- CCO²
- Doxygen
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Answer: D) oxygen
Q32. concentrated solution of which of the following is kept in a fire extinguisher along with concentrated sulphuric acid kept in a bottle?
- Acalcium carbonate
- Bsodium chloride
- Csodium bicarbonate
- Dsodium sulphate
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Answer: C) sodium bicarbonate
Q33. In a simple fire extinguisher, CO is produced by the reaction of:
- ALimestone and dilute sulphuric acid
- BMarble and dilute salt acid
- Csodium bicarbonate and dilute coagulation
- DRatio of sodium carbonate and dilute salt
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Answer: C) sodium bicarbonate and dilute coagulation
Q34. Which gas is used in fire fighting?
- Ahelium
- BCO²
- CCO
- DO²
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Answer: B) CO²
Q35. Water cannot extinguish burning petrol because
- AA flammable chemical is produced when petrol and water are mixed.
- BBurning petrol instantly turns water into steam.
- CPetrol floats on water due to its relatively low density.
- DOn contact with burning petrol, water releases oxygen, which helps in burning.
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Answer: C) Petrol floats on water due to its relatively low density.
Q36. Which of the following is not a fuel element?
- AUranium
- BThorium
- CRadium
- Dhelium
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Answer: D) helium
Q37. Which of the following is not a fossil fuel?
- ACoal
- Bpetroleum
- Cnitrogen
- Dwater gas
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Answer: C) nitrogen
Q38. Which of the following is the best fuel in terms of energy released per gram of fuel?
- Ahydrogen
- Bmethane
- CEthanol
- Dbutane
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Answer: A) hydrogen
Q39. Producer gas is a mixture of—
- ACO+N²
- BCO² + N²
- CCO² + H²+ N²
- DCO²+ H²
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Answer: A) CO+N²
Q40. Which of the following can be used as propellant or fuel in rockets?
- ALiquid Hydrogen + Liquid Nitrogen
- BLiquid Oxygen + Liquid Argan
- Cliquid nitrogen + liquid oxygen
- Dliquid hydrogen + liquid oxygen
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Answer: D) liquid hydrogen + liquid oxygen
Q41. Which of the following fossil fuels is the cleanest fuel?
- ACoal
- Bpetrol
- Cnatural gas
- Ddiesel
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Answer: C) natural gas