Question

D. Write True or False against each statement :
1. Combustion is a chemical process in which a substance reacts to give off heat
2. The calorific value of hydrogen gas is 65000 kj/kg.
3. Oxygen is not essential for combustion
4. LPG is a gaseous fuel.
5. Usually substances catch fire at one fixed temperature.

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Answer 1

Answer:

Ocean currents act as conveyer belts of warm and cold water, sending heat toward the polar regions and helping tropical areas cool off, thus influencing both weather and climate. ... The tropics are particularly rainy because heat absorption, and thus ocean evaporation, is highest in this area

Answer 2

Explanation:

Combustion is a chemical process in which a substance reacts rapidly with oxygen and gives off heat. The original substance is called the fuel, and the source of oxygen is called the oxidizer. The fuel can be a solid, liquid, or gas, although for airplane propulsion the fuel is usually a liquid.