Every question from this NCERT chapter, with a detailed explanation.
A glass plate is introduced into the luminous zone of a candle flame. A circular blackish ring is observed on the plate. What does this indicate?
What is the primary hazard associated with sleeping in a closed room containing a burning coal fire?
With reference to Global Warming, consider the following statements: 1. It is linked to the decreased concentration of carbon dioxide in the air. 2. It results in the melting of polar glaciers and rise in sea levels. 3. Combustion of most fuels releases carbon dioxide. Which of the statements given above are correct?
Which characteristic of Compressed Natural Gas (CNG) makes it a cleaner fuel for automobiles compared to petrol and diesel?
With reference to 'Ignition Temperature', consider the following statements: 1. Ignition temperature is the highest temperature a substance can withstand without burning. 2. A matchstick does not catch fire on its own at room temperature. 3. Kerosene oil has a lower ignition temperature than wood. Which of the statements given above is/are correct?
Consider the following chemicals: 1. Antimony trisulphide 2. Potassium chlorate 3. White phosphorus 4. Red phosphorus Which of the chemicals given above are present in the head of a modern safety matchstick?
With reference to the mechanism of lighting a safety matchstick, consider the following statements: 1. The rubbing surface contains powdered glass and red phosphorus. 2. Upon striking, the red phosphorus remains chemically unchanged. 3. White phosphorus reacts with antimony trisulphide to produce oxygen. Which of the statements given above is/are correct?
Which of the following substances are classified as 'Inflammable Substances'? 1. Petrol 2. Alcohol 3. Liquified Petroleum Gas (LPG) 4. Charcoal Select the correct answer using the code given below:
With reference to fire control, consider the following statements: 1. Fire can be controlled by removing fuel, air, or heat. 2. In all fire accidents, the fuel can be easily removed from the site. 3. Water helps in extinguishing fire by bringing the temperature of the fuel below its ignition temperature. Which of the statements given above is/are correct?
What is the primary reason why water is not used to extinguish fires involving live electrical equipment?
Consider the following statements regarding the use of water to extinguish oil and petrol fires: 1. Water is effective for oil fires because it forms a blanket over the oil. 2. Water is heavier than oil, so it sinks below the oil, allowing the oil to keep burning on top. Which of the statements given above is/are correct?
Why is Carbon Dioxide (CO2) considered an effective fire extinguisher for fires involving electrical equipment and inflammable materials?
With reference to the action of Carbon Dioxide (CO2) extinguishers, consider the following statements: 1. When released from a cylinder, CO2 contracts in volume and heats up. 2. The expansion of CO2 cools down the temperature of the fuel. 3. Dry powder of chemicals like sodium bicarbonate can be used to release CO2 near a fire. Which of the statements given above are correct?
Consider the following statements regarding Spontaneous Combustion: 1. It occurs when a material bursts into flames without the application of any apparent cause. 2. Iron metal burns spontaneously at room temperature. 3. Sand dust in deserts undergoes spontaneous combustion. Which of the statements given above are correct?
With reference to 'Explosion', consider the following statements: 1. It involves the evolution of heat, light, and sound. 2. No gas is evolved during the reaction. 3. It can be triggered by applying pressure on a cracker. Which of the statements given above are correct?
Which of the following materials forms a flame on burning? 1. Magnesium 2. Camphor 3. Charcoal 4. Coal Select the correct answer using the code given below:
Consider the following statements regarding the structure of a candle flame: 1. The innermost zone is the zone of complete combustion. 2. The middle zone is the zone of partial combustion. 3. The outer zone is the hottest part of the flame. Which of the statements given above is/are correct?
What is the primary reason goldsmiths utilize the outermost zone of a flame for melting gold and silver?
With reference to 'Fuels', consider the following statements: 1. A good fuel is one which is readily available and cheap. 2. An ideal fuel burns in air explosively. 3. Compressed Natural Gas (CNG) is considered a completely ideal fuel in all respects. Which of the statements given above are correct?
Consider the following statements regarding calorific values of fuels: 1. LPG has a higher calorific value than wood. 2. Cow dung cake has a higher calorific value than coal. Which of the statements given above is/are correct?
Which one of the following fuels has the highest calorific value?
With reference to the harmful effects of burning fuels, consider the following statements: 1. Burning of carbon fuels like wood and coal releases unburnt carbon particles. 2. These fine particles are beneficial for respiratory health. 3. Incomplete combustion of these fuels produces carbon monoxide gas. Which of the statements given above is/are correct?
Consider the following statements regarding Acid Rain: 1. It is caused by oxides of sulphur and nitrogen dissolving in rain water. 2. Burning of coal and diesel releases oxygen gas only. 3. Petrol engines release water vapour as the only exhaust gas. Which of the statements given above are correct?
Which of the following pairs is correctly matched? Substance | Property 1. Magnesium | Burns to form Magnesium Oxide 2. Charcoal | Vaporizes to form a flame 3. Kerosene Oil | Inflammable substance 4. Wood | High Calorific Value (compared to Coal)
Consider the following statements about the history of matchsticks: 1. Ancient Egyptian matches used pinewood dipped in sulphur. 2. Modern safety matches use white phosphorus on the matchstick head. 3. Red phosphorus is less dangerous than white phosphorus. Which of the statements given above is/are correct?
When a copper wire is held just inside the non-luminous zone of a flame, it gets red hot. What does this observation indicate?
Consider the following statements regarding the burning of a candle: 1. It burns with a flame because the wax remains in solid state during burning. 2. The flame goes off if the air supply is cut off. 3. Unburnt wax vapours are found in the innermost zone of the flame. Which of the statements given above is/are correct?
Which one of the following is a liquid fuel traditionally used for domestic purposes?
With reference to the burning of wood, consider the following statements: 1. Wood is primarily used as an industrial fuel and rarely for domestic purposes. 2. Its use is being replaced by coal and LPG. 3. Burning wood produces smoke which causes respiratory problems. Which of the statements given above is/are correct?
Consider the following statements regarding the ignition of a safety matchstick: 1. The head of a safety matchstick contains white phosphorus. 2. Potassium chlorate releases oxygen to support combustion. 3. Antimony trisulphide acts as the oxidizing agent. Which of the statements given above is/are correct?
Consider the following statements regarding the 'Blue Zone' of a flame: 1. It is the zone of complete combustion. 2. It is the moderately hot zone of the flame. 3. It is the outermost zone of the flame. Which of the statements given above is/are correct?
Which one of the following substances is known to undergo spontaneous combustion in air at room temperature?
Consider the following statements regarding the burning of magnesium and charcoal: 1. Magnesium burns to form magnesium oxide and produces heat and light. 2. Charcoal burns in air to produce oxygen gas. 3. Both magnesium and charcoal burn with a distinct flame. Which of the statements given above are correct?
What is the primary scientific reason for wrapping a blanket around a person whose clothes have caught fire?
What is the mechanism by which a safety matchstick ignites when rubbed against the striking surface?
Consider the following statements regarding 'Combustion': 1. It is a chemical process. 2. It always produces a flame regardless of the substance. 3. It requires a combustible substance. Which of the statements given above is/are correct?
Which one of the following is not an essential requirement for the production of fire?
Consider the following statements about Carbon Monoxide (CO): 1. It is produced by the incomplete combustion of fuels. 2. It is a non-poisonous gas. 3. It is beneficial for human health if inhaled. Which of the statements given above is/are correct?
Match List I with List II and select the correct answer using the code given below: List I | List II A. Magnesium | 1. Burns with a flame B. Charcoal | 2. Evolution of heat, light, sound, gas C. White Phosphorus | 3. Spontaneous combustion at room temperature D. Explosion | 4. Glows, does not flame
Consider the following statements regarding the use of Compressed Natural Gas (CNG): 1. It is used as a fuel for automobiles. 2. It causes more pollution than petrol. 3. It has a higher calorific value than wood. Which of the statements given above is/are correct?
What is the primary reason that charcoal burns without producing a flame?
With reference to the zones of a candle flame, the 'Luminous Zone' is characterized by:
Consider the following statements regarding the environmental impact of burning fuels: 1. Oxides of sulphur and nitrogen are beneficial for soil fertility. 2. Acid rain is harmful to crops, buildings, and soil. 3. Deforestation leads to an increase in the concentration of carbon dioxide in the atmosphere. Which of the statements given above is/are correct?
What is the primary mechanism by which water extinguishes fires involving wood or paper?
Consider the following statements about 'Combustible Substances': 1. Wood and paper are combustible substances. 2. Glass is a highly combustible substance. 3. Stone and iron nails are combustible substances. Which of the statements given above is/are correct?
Which one of the following processes best describes the mechanism behind the explosion of fireworks?
With reference to the 'Dark Zone' of a candle flame, consider the following statements: 1. It is located around the wick. 2. It is characterized by the complete combustion of wax vapours. 3. It is the hottest part of the flame. Which of the statements given above is/are correct?
Which one of the following fuels is primarily produced from the anaerobic degradation of cattle dung?
Consider the following statements regarding the efficiency of fuels: 1. Fuel efficiency is expressed in terms of its calorific value. 2. A fuel with a higher calorific value produces significantly less heat per unit mass. 3. Hydrogen has a higher calorific value than Diesel. Which of the statements given above is/are correct?
What is the function of Sodium Bicarbonate when used in fire extinguishers?
Consider the following statements about 'Acid Rain': 1. It is primarily caused by the dissolution of carbon dioxide in rain water. 2. It is harmful to soil and buildings. 3. It is caused by oxides of sulphur and nitrogen. Which of the statements given above is/are correct?
Why are materials like paper or kerosene oil often required to initiate the burning of wood or coal?
Consider the following statements regarding the 'Sun': 1. It produces heat and light. 2. The process involved is a chemical combustion reaction. 3. The process involved is nuclear fission. Which of the statements given above is/are correct?
In an experiment demonstrating the necessity of air for combustion, what is the primary function of placing a glass chimney over a burning candle?
Which one of the following properties is a characteristic of an ideal fuel?
With reference to the 'Middle Zone' of a candle flame, consider the following statements: 1. It is the non-luminous zone of the flame. 2. It is the zone of partial combustion. 3. It is yellow in colour. Which of the statements given above is/are correct?
What does the term 'Ignition Temperature' refer to?
Which one of the following gases is primarily responsible for the phenomenon of Global Warming?