Answer:
the chemical element of atomic number 2, an inert gas which is the lightest member of the noble gas series.
Step-by-step explanation:
Because it is very unreactive, helium is used to provide an inert protective atmosphere for making fibre optics and semiconductors, and for arc welding. Helium is also used to detect leaks, such as in car air-conditioning systems, and because it diffuses quickly it is used to inflate car airbags after impact.