The smoke emanating from ammonium chloride powder used for cleaning hot utensils while galvanizing brass utensils is

Correct answer: (d) Ammonia and hydrochloric acid

Explanation

When ammonium chloride (sal ammoniac) is sprinkled on a hot metal surface, it breaks down into ammonia and hydrogen chloride:

NH₄Cl → NH₃ + HCl

These form the white fumes. The hydrogen chloride removes the oxide film from the metal, which is why sal ammoniac is used to clean the surface before tinning or coating (kalai) utensils.