Question

Why is Hydrogen called inflammable air?

Answer 1

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. The degree of flammability or combustibility in air is primarily determined by the material's volatility, which is linked to its composition-specific vapour pressure, which varies with temperature.

Complete answer:
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.
Because hydrogen is a highly flammable gas, it is referred to as inflammable air. The safe production, handling, and use of hydrogen - notably hydrogen gas fuel and liquid hydrogen - is covered under hydrogen safety. When working with hydrogen, the major problem is flammability. Because hydrogen is flammable when mixed even in small amounts with ordinary air, it receives the highest NFPA 704 flammability rating of 4; ignition can occur at a volumetric ratio of hydrogen to air as low as 4% due to the oxygen in the air and the simplicity and chemical properties of the reaction.
Hydrogen is a very flammable gas. Unless the escape occurs in a contained, unventilated location, however, this is reduced by the fact that hydrogen rises quickly and disperses often before igniting. In contrast to what might be expected in a gasoline-fueled car, demonstrations have demonstrated that a fuel fire in a hydrogen-powered vehicle may burn out entirely with no harm to the vehicle.

Note:
Because hydrogen has no odour, colour, or taste, most human senses will be unable to notice a leak. Natural gas, on the other hand, is odourless, colourless, and tasteless, but industry adds a sulfur-based odorant called a mercaptan to make it perceptible by humans. Fuel cells are now contaminated by all known odorants (a popular application for hydrogen). However, because hydrogen rises fast, a hydrogen leak indoors would first gather on the ceiling before moving to the corners and away from areas where humans may be exposed.