InterviewSolution
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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
What are the different zones present in a candles and what are the colours of those zones? |
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Answer» There are three zones in a candle. 1. Outermost zone: This is the hottest part which is in blue colour. 2. Middle zone: This is moderately hot part which is in yellow colour. 3. Dark zone: This is least hot part which is in black colour. |
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| 52. |
Observing the structure of the flame. Light a wax candle and watch the flame.Carefully note the different coloured zones in the flame.a) How many colours are there in the flame?b) Starting from the base of the flame, how many flame zones do you observe? What is the colour of the outer most zone of the flame?c) Observe the innermost zone which is dark. What do you observe there? |
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Answer» a) There are three colours in the flame. b) There are three flame zones are observed. The colour of outermost zone is blue. c) In this zone wax gets vapourised. This is dark zone. Observe near the base of the flame. Vaporized wax gets completely oxidized and burns with a blue flame. It is blue zone. |
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| 53. |
Observing what happens in different zones of candle flame.Light a candle. Hold a glass tube (with 7 cm length) a pair of tongs and introduce its one end in the dark zone of a non flickering candle flame. Keep lighted match stick near the other end of the glass tube as shown in the figure. a) What do you observe? Do you see a flame? If so what is it, that produces a flame?b) Notice that the wax near the heated wick melts quickly. What do you observe?c) What is it?d) Hold a thin long copper wire just inside the flame for about half a minute. What do you observe? What is your inference? |
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Answer» a) Yes, the some of vapours produced by wax pass through the glass tube and are burnt by match stick to produce flame. b) When the candle’s flame is steady introduce a clean glass slide into the luminous zone of the flame and hold it with a pair of tongs for 10 seconds. A blackish circular ring is formed on the glass slide. c) The deposition of unburnt carbon particles present in the luminous zone of the flame due to incomplete combustion. d) The copper wire just outside the flame gets red hot. It indicates that the non luminous zone of the flame has high temperature. It is the hottest part of the flame. It is blue in colour and complete combustion takes place due to good supply of oxygen. |
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| 54. |
What do you mean by combustion? |
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Answer» A chemical process in which a material reacts with oxygen present in air to generate heat is called combustion. |
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| 55. |
The units of calorific value is A) Newtons/grams B) Newtons/kg C) Kilo jouls/kg D) Kilo jouls/gram |
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Answer» Correct option is C) Kilo jouls/kg |
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| 56. |
The full form of LPG is A) Liquefied Pilot Gas B) Liquified Petroleum Gas C) Liquid Petrol Gas D) Liquid Potential Gas |
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Answer» Correct option is B) Liquified Petroleum Gas |
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| 57. |
………… is written on petrol tankers, A) Flammable B) Inflammable C) Highly inflammable D) None of these |
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Answer» Correct option is C) Highly inflammable |
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| 58. |
………… zone of candle is least hot. A) Middle zone B) Outermost zone C) Dark zone D) None of these |
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Answer» Correct option is C) Dark zone |
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| 59. |
Spirit and petrol turn into …………. at room temperature. A) solid B) liquid C) gas D) none of these |
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Answer» Correct option is C) gas |
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| 60. |
Burning of gas is an example of …………. combustion. A) spontaneous B) rapid C) regular D) irregular |
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Answer» Correct option is B) rapid |
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| 61. |
The dark zone of candle is …………… in colour. A) blue B) black C) red D) yellow |
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Answer» Correct option is B) black |
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| 62. |
…………. zone is the hottest part of the candle. A) Innermost B) Middle C) Outermost D) None of these |
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Answer» Correct option is C) Outermost |
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| 63. |
Middle zone of candle is ……….. in colour. A) Blue B) Red C) Yellow D) White |
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Answer» Correct option is C) Yellow |
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| 64. |
The colour of flame of candle at hottest zone isA) Red B) Blue C) Yellow D) White |
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Answer» Correct option is B) Blue |
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| 65. |
What do you know about Explosion? |
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Answer» Explosion: The reaction ¡n which there is the liberation of heat, light, sound, and a large amount of gas is called an explosion. |
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| 66. |
Which one of the following has the highest calorific value? A) Kerosene B) BiogasC) LPG D) Petrol |
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Answer» Correct option is C) LPG |
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| 67. |
What is explosion? |
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Answer» A chemical reaction takes place with the evolution of heat, light, sound and large amount of gas is called explosion. |
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| 68. |
One of the following substances is expected to have the highest ignition temperature A) Kerosene B) Petrol C) Coal D) Alcohol |
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Answer» Correct option is C) Coal |
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| 69. |
What are inflammable substances? Give examples. |
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Answer» The substance which have very low ignition temperature easily catch fire are called inflammable substances, e.g.: Petrol, alcohol, LPG, etc. |
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| 70. |
What is called by Inflammable material? |
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Answer» Inflammable material: The material which has a very low ignition temperature easily catches fire called an inflammable material. |
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