Concentrated hydrochloric acid when kept in open air sometimes produces a cloud of white fumes. The explanation for it is that:

Name the following:
(i) Acid present in the stomach of mammals.
(ii) Drying agent used to dry hydrogen chloride.
(iii) Salt obtained by heating sodium chloride with concentrated sulphuric acid below 200 degree celsius.
(iv) Gas that yields dense white fumes when mixed with hydrogen chloride.
(v) Two solution that yield white precipitates, when treated with hydrogen chloride or hydrochloric acid.
(vi) Gas obtained by treating metals with hydrochloric acid.
(vii) Gas obtained by treating ferrous sulphide with hydrochloric acid.
(viii) Five oxidizing agents that liberate chlorine from concentrated hydrochloric acid.
(ix) Acid used to extract glue from bones.
(x) A chloride which is soluble in excess of ammonium hydroxide.
(xi) A greenish yellow gas.
(xii) A chemical in which gold can be dissolved.
(xiii) A metallic oxide which reacts with hydrochloric acid to give a coloured solution.
(xiv) Two colourless gases which when mixed produce a white solid.

When a glass rod dipped in ammonia solution is brought near vapours of hydrochloric acid we see the formation of a dense white fume. What is this dense white fume?