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प्रश्न
Complete the crossword with the help of the clues.
Across
1. Non-metal which catches fire if exposed to air. (10)
3. The lowest temperature at which a substance catches fire is called its ______ temperature. (8)
5. The most common fire extinguisher. (5)
Down
2. A chemical process in which a substance reacts with oxygen to give off heat. (10)
4. Petrol is used as a ______ in automobiles. (4)
6. It is as hard as stone and black in colour. (4)
उत्तर
Across
1. Phosphorus
3. Ignition
5. Water
Down
2. Combustion
4. Fuel
6. Coal
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संबंधित प्रश्न
List conditions under which combustion can take place.
A ______ process in which a substance reacts with ______ to give off heat is called combustion.
Some words (underlined) in the following sentence is jumbled up. Write them in their correct form.
Slaags is a non-combustible material.
Some words (underlined) in the following sentence is jumbled up. Write them in their correct form.
Some substances on combustion produce thea and mafel.
Two glass jars A and B are filled with carbon dioxide and oxygen gases respectively. In each jar, a lighted candle is placed simultaneously. In which jar, will the candle remain lighted for a longer time and why?
Write True/False against the following statement and also correct the false statement.
Increased concentration of nitrogen in air is believed to cause global warming.
Which of the following conditions is not necessary for combustion?
Any reaction that involves reaction with oxygen is called reaction ______.
Give one example of slow combustion.
Fill in the blanks using the words given in the box.
| ignition | petrol | combustion | calorific value | combustible | combustible |
Ignition temperature of ______ is lower than that of wood.
