QJEEAdv19Ch2347: JEE Advanced 2019 Chemistry - Class 12 JEEAdv19Ch2347 Solution: With reference to aqua-regia, choose the correct option(s).

The explanation of given statements are as follows :

(a) Aqua-regia is prepared by mixing conc. HCl and conc. HNO₃ in 3 : 1 (v/v) ratio and is used in oxidation of gold and platinum. Hence, option (a) is correct.

(b) Yellow colour of aqua-regia is due to its decomposition into NOCl (orange yellow) and Cl₂ (greenish yellow). Hence, option (b) is correct.

(c) When gold reacts with aqua-regia then it produces $$AuC{l}_4^{-}$$ anion complex in which Au has +3 oxidation state.



Hence, option (c) is correct.

(d) Reaction of gold with aqua-regia produces NO gas in absence of air. Hence, option (d) is incorrect.