Question

Which of the following is not correct for noble gas?

• A. Argon is used in electric bulb.
• 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

The correct option is B Krypton is obtained during radioactive disintegration.

Traces of krypton are found in various minerals, the most important source of Krypton is Earth's atmosphere. Air is also the source for the other noble gases, with the exception of helium which obtained from natural gas and radon which is obtained as a byproduct of the decay of radioactive elements

So Krypton is not obtained during radioactive disintegration. It is radon formed during radioactive disintegration.

Hence option $B$ is correct.