Ncert – class 8- science – Chapter 4: Combustion and Flame 2 Welcome to your Ncert - class 8- science - Chapter 4: Combustion and Flame 2 1. Match column 'A' with column 'B', concerning the characteristics of a flame and its zones. 'A' 'B' a. Dark inner zone 1. Hottest part (No carbon) b. Blue zone 2. Partial combustion c. Luminous zone 3. Unburnt vapours of wax d. Non-luminous zone 4. Complete combustion a - 4, b - 1, c - 2, d - 3 a - 2, b - 3, c - 4, d - 1 a - 3, b - 4, c - 2, d - 1 a -1, b - 2, c - 3, d - 4 None 2. What kind of combustion is undergone by ignition of a cracker? Spontaneous combustion Slow combustion Explosive combustion Rapid combustion None 3. What is an ideal fuel? All of the above It has high calorific value. It is readily combustible. It is cheap. None 4. Why are the spirit and kerosene lamps made in such a way that the free end of the wicks with the flame remains totally cut off from the fuel?i)The fuel vaporization in room temperature ii)The fuel is highly inflammable ii) The calorific value of fuel can be increased. (i), (ii) and (iii) Only (i) and (iii) Only (i) and (ii) Only (ii) and (iii) None 5. Which of the following is not true about combustion? In case of chimney candle burns freely when air enters from below the chimney. In the absence of air candles flame flickers but does not goes off. In case of chimney when air does not enters from below, the candle burns freely. In case of chimney when air does not enters from below, the flame flickers and produces smoke. None 6. What is calorific value? Amount of heat energy consumed on complete combustion of 1 g of fuel. Amount of heat energy produced on complete combustion of 100 kg of fuel. Amount of heat energy consumed on complete combustion of 1 kg of fuel. Amount of heat energy produced on complete combustion of 1 kg of fuel. None 7. Which of the following is not true about combustion? In the absence of air candles flame flickers but does not goes off. In case of chimney, candle burns freely when air enters from below the chimney. In case of chimney, when air does not enter from below, the candle burns freely. In case of chimney, when air does not enter from below, the flame flickers and produces smoke. None 8. Shyam was cooking potato curry on a chulha. To his surprise, he observed that the copper vessel was getting blackened from outside. It may be due to: proper combustion of fuel improper combustion of the fuel burning of copper vessel improper cooking of potato curry None 9. Which of the following statements is true? Water extinguishes a fire in two ways: (1) It brings the temperature of the combustible material below its ignition temperature. (2) The water vapour formed due to the heat of fire cuts the supply of oxygen. Both Carbon dioxide is highly volatile. So, it immediately vaporises to cut off the supply of air. In the absence of supporter of combustion, fire is extinguished. None None 10. If you fix a burning candle on a petri dish, it will continue to burn, but when you put an inverted beaker over it, the flame goes off. Why does this happen? Both None Insufficient nitrogen in the air. The supply of oxygen is cut off. None 11. Which of the following statement is not correct? Burning of wood can be stopped by covering it with sand Burning of coal cannot be stopped by covering it with sand The flame of a burning candle can be put off by placing a cover cap over the flame Air is essential for the burning process None 12. Combustion is a ________ reaction accompanied by heat and light. oxidation substitution reduction redox None 13. Which type of fire extinguisher is used to extinguish fire caused by burning oil and petrol? Water type Foam type CCl4 type Soda acid type None 14. Gasoline combusts in the presence of oxygen. Identify whether Combustion is a physical property or chemical property This is a physical property. This is neither a physical nor a chemical property. There is not enough information to tell if this is a physical or chemical property. This is a chemical property. None 15. When paper is wrapped around an Aluminium pipe ____________. ignition temperature reduces ignition temperature increase no change in ignition temperature the paper and aluminium catches fire very easily None Time's up Please Share This Share this content Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Opens in a new window Leave a Reply Cancel replyCommentEnter your name or username to comment Enter your email address to comment Enter your website URL (optional) Save my name, email, and website in this browser for the next time I comment.
