Choose the most appropriate answer from the following list of substances which fits best in the description.

[Silver chloride, ammonium chloride, aqua-regia, explosive, N₂ , NCl₃, volatile]

(a) Silver nitrate reacts with hydrochloric acid to give a white precipitate.

(b) The solution formed by the concentrated hydrochloric acid and concentrated nitric acid in the ratio of 3:1.

(c) The property which does not allow conc. HNO₃ used in the preparation of HCl.

For each of the formula of ores given below, what is their common names and role/use.

(a) Al₂O₃.2H₂O

(b) Na₃AlF₆

Raju is going to the laboratory for the preparation of sulphuric acid.

(a) Write the equations for sulphuric acid combining directly with metals and non-metals.

(b) Which concentrated acid will oxidise sulphur directly to sulphuric acid ? Write the equation for the same.

(c) What is the name of the process by which sulphuric acid is manufactured ? Name the catalyst used in the process.

Give reasons

(a) Brass is preferred over copper for door settings.

(b) Metals like iron, aluminium, cobalt and nickel become passive (inert) with concentrated nitric acid.

(c) Alloying of gold is done with silver or copper.