Which of the following is radioactive?

Number of neutrons in a heavy hydrogen atom is

Liquid ammonia is used in refrigeration because of its

Which element accepts one electron to achieve a noble gas-like configuration?

What do you understand by $(i)$ electron deficient,$(ii)$ electron precise,and $(iii)$ electron rich compounds of hydrogen? Provide justification with suitable examples.

How is $H_2S$ prepared in the laboratory using $FeS$?