Study the following table :

Fuel	Calorific value	State	Ignition temp.
A	High	solid	high
B	Moderate	gas	high
C	Moderate	gas	moderate
D	Low	liquid	low

Which is best suited as domestic fuel ?

The correct option is C.

To determine which fuel is best suited as a domestic fuel, we need to evaluate the characteristics of an ideal domestic fuel:

1. Calorific Value: It should be moderate to high so that a sufficient amount of heat energy is produced per unit mass without being uncontrollable or excessively intense for regular cooking and heating needs.
2. State of Matter: Gaseous fuels are preferred for domestic use (like LPG or natural gas) because they burn cleanly without leaving behind ash or residue, are easy to transport through pipes or cylinders, and can be easily controlled using valves.
3. Ignition Temperature: It should be moderate. If the ignition temperature is too low, the fuel can easily catch fire accidentally (high safety risk). If it is too high, it becomes difficult to ignite for daily household tasks.

Now, let us analyze the data given in the table for each fuel:

- Fuel A: High calorific value, solid state, and high ignition temperature. Solid fuels leave residue/ash and a high ignition temperature makes it hard to light.
- Fuel B: Moderate calorific value and gaseous state, but has a high ignition temperature, making it difficult to ignite easily for everyday domestic use.
- Fuel C: Moderate calorific value, gaseous state, and moderate ignition temperature. This combination ensures efficient, clean combustion with easy ignition and safe handling, making it ideal for domestic fuel.
- Fuel D: Low calorific value and low ignition temperature. A low ignition temperature poses a safety risk, and low calorific value means poor heating efficiency.

Therefore, Fuel C is the best suited domestic fuel.