Question

A rare gas that was detected on in the sun before its discovery on earth is:
A. He
B. Ne
C. Ar
D. Kr

Answer 1

Hint: Neon, krypton and xenon, the rare or noble gases, are only present in the air in trace amounts. Air contains just 0.0018% neon, 0.00011% krypton and 0.000009% xenon. The rare gases, also known as the noble gases or the inert gases, are a group of six gaseous elements found in small amounts in the atmosphere: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). Collectively they make up about one percent of Earth’s atmosphere.

Complete step by step answer:
Helium is a chemical element with the symbol He and atomic number 2. It is colorless, odorless, tasteless, nontoxic, inert, monoatomic gas, the first in the noble gas group in the periodic table. Its boiling point is lower among all the elements. Helium, the second most abundant element in the universe was discovered on the sun before it was found on the earth. Pierre Jules Cesar Janssen, a French astronomer, noticed a yellow line on the sun’s spectrum while studying a total solar eclipse in 1868.

Helium is present at about 24% of the total elemental mass, which is more than 12 times the mass of all the heavier elements combined. Its abundance is similar to this in both the Sun and Jupitar. This is due to very heavy nuclear binding energy of helium-4, with respect to the next three elements after helium.

So, of all the noble gases, first comes the discovery of helium, which is unique in being the first element to be discovered extra -terrestrially before being found on the earth.

SO, the correct answer is A.

Note:
A. Neon is also a chemical element with symbol Ne and atomic number 10. It is a noble gas. Neon is a colorless, odorless, inert monatomic gas under standard condition with about two-third of the density of air.
B. Argon is a chemical element with the symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third most abundant gas in the earth’s atmosphere, at 0.934%.
C. Krypton is a chemical element with the symbol Kr and atomic number 36. It is colorless, odorless, tasteless, noble gas that occurs in trace amounts in the atmosphere and is often used with other rare gases in fluorescent lamps. With rare exceptions, Krypton is chemically inert.