Question

The elements that are combustible in the fuel are-
A.Carbon and hydrogen
B.Carbon, hydrogen and ash
C.Carbon, hydrogen and sulphur
D.Carbon, nitrogen and ash

Answer 1

Hint: Any material that may be made to react with other substances to release energy as thermal energy or to be used for work is referred to as a fuel. The idea was first applied to materials that could release chemical energy, but it has subsequently been expanded to include other types of heat energy, such as nuclear energy (via nuclear fission and nuclear fusion).
Complete solution
A heat engine can transform the heat energy generated by fuel reactions into mechanical energy. Heat is sometimes appreciated for its own sake, such as for warmth, cooking, or industrial operations, as well as for the illumination that comes with combustion. Fuels are also utilised in the cells of animals, where organic molecules are oxidised to produce usable energy in a process known as cellular respiration. Humans employ a variety of fuels, including hydrocarbons and similar organic compounds, but other substances, such as radioactive metals, are also used.
Combustible compounds are those that burn in the presence of oxygen and heat, whereas non-combustible chemicals are those that do not. The presence of elements like carbon, hydrogen, and sulphur in the fuel makes it flammable. A combustible substance is one that can burn (combust) in the presence of air. Combustible materials that ignite quickly at room temperature are known as flammable materials. In other words, a combustible substance takes some effort to ignite, but a flammable material ignites instantly when exposed to flame.

Hence option c is correct.

Note:
The ease with which a flammable substance can be ignited, resulting in fire, combustion, or even an explosion, is known as flammability. Fire testing is used to determine the degree of difficulty necessary to induce a material to burn. To measure flammability, a number of test procedures are used across the world. Construction rules, insurance requirements, fire codes, and other restrictions controlling the use of building materials, as well as the storage and handling of highly flammable chemicals within and outside of structures, as well as in surface and air transportation, employ the ratings obtained.