Noble metals, like gold and platinum are soluble in which of the following mixtures?

Noble metals, like gold and platinum are soluble in which of the following mixtures?
  1. \(1: 1\) mixture of conc. \(\mathrm{HNO}_3\) and conc. \(\mathrm{H}_2 \mathrm{SO}_4\)
  2. \(1: 3\) mixture of conc. \(\mathrm{HCl}\) and conc. \(\mathrm{HNO}_3\)
  3. \(1: 3\) mixture of conc. \(\mathrm{HNO}_3\) and conc. \(\mathrm{HCl}\)
  4. \(1: 3\) mixture of conc. \(\mathrm{H}_2 \mathrm{SO}_4\) and conc. \(\mathrm{HCl}\)

Solution

Nobel metal such as gold and platinum are soluble in aqua-regia which is a mixture of nitric acid and hydrochloric acid in molar ratio of \(1: 3\). i.e. \(3 \mathrm{HCl}+1 \mathrm{HNO}_3=\) aqua-regia Hence, option (3) is correct.

Asked in: AP EAMCET 2019 (20 Apr Shift 1)

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