Question

Which of the following is not correct for noble gas?
A) Argon is used in electric bulbs.
B) Krypton is obtained during radioactive disintegration.
C) Half-life of radon is 3.8 days.
D) Helium is used to produce low temperature.

Answer 1

Hint: During the radioactive disintegration process, the product obtained has a high atomic number. Also consider the uses of various noble gases. Noble gases have fully filled orbitals.

Complete answer:
Argon is used in electric bulbs, fluorescent and incandescent lights. In the presence of inert atmosphere of argon, oxygen cannot corrode the hot tungsten filament. This prevents evaporation of tungsten and increases the life of the bulb.
Half-life of radon is 3.8 days. After 3.8 decays, one half of radon sample decays and one half remains.
Helium becomes liquid at 4K and can be used to produce the low temperature needed in material study and for cooling coils of superconducting magnets.
Several minerals contain traces of krypton. Earth’s atmosphere is the most important source of krypton. Air contains several noble gases. Helium and radon are not present in the air. The source of helium is natural gas. The source of radon is the radioactive decay process.
Since Krypton is not obtained during the radioactive decay process.

Thus the option (B) represents an incorrect statement for noble gases.

Note: Noble gases are chemically inert gases. These gases do not react as they have completed their octet. Noble gases belong to group 18 in the periodic table. The six naturally occurring noble gases helium, neon, argon, krypton xenon and the radioactive radon.