Question

18. A copper coin is kept in a solution of silver nitrate
for some time. What will happen to the coin and the
colour of the solution?
19. What happens when zinc granules are treated with
dilute solution of H2 SO4, HCL HNO,3 NaCl and
NaOH? Also write the chemical equation if occurs.
NCERT Exemplar
21.​

Answer 1

18) copper coin will get a shining greyish white coating of silver metal. The color of the solution will turn blue

19)

Answer 2

Answer:

18. When a copper coin is kept in silver nitrate solution copper displaces silver from silver nitrate solution and the coin get shining grey white coating. The colour of the solution will be blue.

19.Hydrogen gas and zinc sulphate are formed when zinc granules are treated with sulphuric acid.

Zinc chloride and hydrogen gas are formed, when zinc granules are treated with hydrochloric acid.

.Zn + 2HCl ⇨ ZnCl2 + H2

Similarly, hydrogen gas and zinc nitrate are formed when zinc granules are treated with nitric acid.

Zn + 2HNO 3 ⇨ Zn (NO 3 ) 2 + H 2

Since, zinc is less reactive than sodium, thus no reaction takes place when zinc granules are treated with sodium chloride.

Sodium zincate and hydrogen gas are formed when zinc granules are treated with sodium hydroxide and water.

Zn + 2H2O + 2NaOH ⇨ Na2 Zn(OH)4 + H2

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