Question

Silver articles become black on prolonged exposure to air. This is due to the formation of
(a) Ag3N
(b) Ag2O
(c) Ag2S
(d) Ag2S and Ag3N

NCERT Class X
Science - Exemplar Problems

Chapter_Metals and Non Metals

Answer 1

  (c) Silver article become black because silver reacts with H2s gas present in air to form black coating of Ag2s


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Answer 2

Answer : The correct option is, (c) $Ag_2S$

Explanation :

When the silver react with the hydrogen sulfide gas that is present in the air to form a black coating of silver sulfide. Silver sulfide are insoluble in all the solvents.

The balanced chemical reaction will be,

$2Ag(s)+H_2S(g)\rightarrow Ag_2S(s)+H_2(g)$

By the stoichiometry, 2 moles of silver react with the 1 mole of hydrogen gas to give 1 mole of silver sulfide and 2 moles of hydrogen gas.

Hence, the correct option is, (c) $Ag_2S$