Question

The compound used in Hawker's lamp and in light houses for illumination purposes is:
A. Methane
B. Ethane
C. Ethylene
D. Acetylene

Answer 1

Hint : Hawker's lamps are those lamps used by street hawkers. These street hawkers generally sell goods like fruits and vegetables on the street. These lamps are actually Carbide lamps or Acetylene gas lamps. The combustion reaction undergone by the gas in the lamps is what produces light from the lamps.

Complete Step By Step Answer:
Hawker's lamps use Acetylene. Acetylene is an alkyne, having the formula $\left( {{C_2}{H_2}} \right).$ It is also known as Ethyne. It is the simplest alkyne. Acetylene exists as a colourless gas and its wide usage is in the form of fuel. In Hawker's lamps, the light produced is by the reaction between three compounds: acetylene, calcium carbide and water. The chemical reaction can be explained in two steps:
Step $1:$ Acetylene is produced by reaction between calcium carbide and water.
$Ca{C_{2(s)}}\; + {\text{ }}2{H_2}{O_{(l)}}\; \to \;{C_2}{H_2}_{(g)}\; + \;Ca{\left( {OH} \right)_2}_{(aq)}$
Step $2:$ Combustion acetylene in air
$2{C_2}{H_2}\; + {\text{ }}5{O_2}\; \to {\text{ }}4C{O_2}\; + {\text{ }}2{H_2}O{\text{ }}\left( { + \;\Delta H\; = {\text{ }} - 1300\;kJ/mol} \right)$
An acetylene gas powered lamp produces a bright light. The combustion reaction is fairly exothermic, giving off enough heat and light.
Hence, the required answer for the question "the compound used in Hawker's lamp and in light houses for illumination purposes is:" option D. Acetylene.

Note :
Acetylene gas lamps or carbide lamps were used to illuminate buildings. They were used as lighthouse beacons, as headlights on motor-cars as well as bicycles. Once they became portable, they were worn on hats and also carried by hand. This became widely useful in mining in the early twentieth century. In India, these lamps are used by street vendors, allowing them to sell their goods even at night.