Concentrated $HNO_3$ turns brown on standing due to the formation of:

$A$ colourless gas with the smell of rotten fish is

In which of the following arrangements,the order is not strictly according to the property written against it?

Which of the following reacts with $Fe(II)$ ions to form a brown complex?

Which of the following, when subjected to thermal decomposition, will liberate dinitrogen?
$(i)$ Sodium nitrate
$(ii)$ Ammonium dichromate
$(iii)$ Barium azide

What happens when a large amount of water is added to a solution of $BiCl_3$?