Q. Can the process of rusting be called combustion? Discuss.

Q. Compare LPG and wood as fuels.

Q. Abida and Ramesh were doing an experiment in which water was to be heated in a beaker. Abida kept the beaker near the wick of the candle flame. Ramesh kept the beaker on the outermost part of the flame. Whose water will get heated in a shorter time?

Q. Name the unit in which the calorific value of a fuel is expressed.

Q. Fill in the blanks:
(a) Burning of wood and coal causes _____ of air.
(b) A liquid fuel, used in homes is _____ .
(c) Fuel must be heated to its _____ before it starts burning.
(d) Fire produced by oil cannot be controlled by ______ .

Q. List conditions under which combustion can take place.

Q. In an experiment $4.5$ kg of a fuel was completely burnt. The heat produced was measured to be $1,80,000$ kJ. Calculate the calorific value of the fuel(in kJ/kg)?

Q. Give reasons
(a) Water is not used to control fires involving electrical equipment.
(b) LPG is a better domestic fuel than wood.
(c) Paper by itself catches fire easily whereas a piece of paper wrapped around an aluminium pipe does not.

Q. How $C{O}_2$ is able to control fire? Explain.

Q. Make a labelled diagram of a candle flame.

Q. Which zone of a flame does a goldsmith use for melting gold and silver and why?

Q. Explain how the use of CNG in automobiles has reduced pollution in our cities.