Question

Helium is preferred for hydrogen for filling balloons because it is
A) Lighter than air
B) Almost as light as hydrogen
C) Non-combustible
D) Inflammable

Answer 1

Hint: Hydrogen is the most abundant element in the universe and helium is the second most abundant element in the universe. Hydrogen accounts for 75% and helium 25% of its matter in the universe.

Complete step by step solution:
Hydrogen is a inflammable gas and sets fire very easily. Highly combustible gas and may cause severe hazard. So filling the balloons with hydrogen gas is highly unsafe. Therefore, we prefer helium gas instead of hydrogen gas to fill the balloons. Option C non-combustible is the correct answer to the given question. Helium gas does not set file easily and is a non-combustible gas. so it is safe to use.

Additional information:-
Hydrogen gas was first artificially produced in the early 16th century by the reaction of acids on metals. Henry Cavendish was the first to recognise that hydrogen gas was a discrete substance and that it produces water when burnt. The property for which it was later named water former. Universal emergence of atomic hydrogen first occurred during the recombination epoch. Hydrogen was liquefied for the first time by James dewar in 1898 by regenerative cooling and his invention, the vacuum flask. He produced solid hydrogen next year. This element is found in great abundance in stars and gas giant planets. Molecular clouds of H2 are associated with star formation. Hydrogen plays a vital role in our stars through proton reaction. Round the universe, hydrogen is mostly found in atomic and plasma States, which property is quite distinct from molecular hydrogen.
First evidence of helium was observed as a bright yellow line in the spectrum of the chromosphere of the sun. In 1881 Italian physicist Luigi palmieri detected helium on Earth for the first time. Most helium on Earth is a result of radioactive decay. Helium is extracted by fractional distillation from natural gas which can contain as much as 7% helium. Speed of sound in helium is three times the speed of sound in the air. Because the natural resonant frequency of a gas filled cavity is proportional to the speed of sound in the gas. Liquid helium is used in cryogenics, particularly in the cooling of superconducting magnets; with the main commercial application being is is scanners. Helium is used as a protective gas in growing silicon and germanium crystals, titanium and zirconium production and in gas chromatography. Because helium is lighter than air, shapes and balloons are inflated with helium. The age of Rock of Uranium and thorium can be estimated by measuring the level of helium with the process known as helium dating.

Note:-
Hydrogen is the lightest element in the periodic table with atomic number 1. With one proton and one neutron. Hydrogen is colourless tasteless non toxic non metallic highly combustible diatomic gas with molecular formula H2. Hydrogen can take the form of a negative charge when it is known as hydride, or is positively donated by the symbol H. Hydrogen gas is very rare in the earth's atmosphere because of its light weight, which enables it to escape from earth gravity more easily than heavier gases. Helium is the second least reactive noble gas after neon, and disliked and least reactive of all elements. Helium is used for many purposes that requires some of its unique properties such as low boiling point low density low solubility high thermal conductivity or inertness. Helium has a valence of zero and is chemically unreactive and acts as an electrical insulator unless ionized.