Question

A reddish brown metal X on heating forms a black coating of oxide Y'on its
surface The metal does not react with dil. HCI and dil H.SO. It reacts with hot
conc H.SO. to give a pungent smelling gas similar to that produced by
burning matchstick. The metal oxide reacts with dil.H.SO, to form a blue
solution. Identify . X. 'Y and Z". Write the chemical reactions involved.
​

Answer 1

Explanation:

metal x is copper

y copper oxide is formed on its surface on heating giving a black coating on copper

2Cu+O2----------> 2CuO

(x) (y)

Answer 2

Answer:

The metal in reddish brown colour is Copper (Cu).

On heating it forms black colored oxide 2Cu + O₂ → CuO

Cu on reaction with conc.H₂SO₄ produces SO₂ gas (pungent smelling gas)

Cu + 2H₂SO₄ → CuSO₄ + SO₂ + 2H₂O

Copper oxide on reaction with dil.H₂SO₄ forms copper sulphate

CuO + H₂SO₄ → CuSO₄ + H₂O

(blue colored solution)

X = Cu

Y = CuO

Z = CuSO₄ + H₂O

Cu reacts with dil.HNO₃ to liberate nitrogen monoxide

Cu + HNO3 →Cu (NO3)2 + H2O + NO (colourless gas)

Cu reacts with conc.HNO₃ to liberate nitrogen dioxide

Cu + 2HNO3 → Cu (NO3)2 + H2O + NO2 (brown colored gas)

A =NO B = NO2

Explanation:

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