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NEET2002Chemistryd and f Block ElementsActual

When CuSO ₄ reacts with KCN it forms CuCN , which is insoluble in water. It is soluble in excess of KCN due to the formation of the following complex:

Options

  1. AK ₂ [ Cu ( CN )₄ ]
  2. BK ₃ [ Cu ( CN )₄ ]
  3. CCuCN ₂
  4. DCu [ KCu ( CN )₄ ]

Correct answer

B. K ₃ [ Cu ( CN )₄ ]

Step-by-step solution

CuSO ₄ reacts with KCN to give a white precipitate of cuprous cyanide and cyanogen gas. The cuprous cyanide dissolves in excess of KCN forming K ₃ [ Cu ( CN )₄ ] gathered CuSO ₄+2 KCN K ₂ SO ₄+ Cu ( CN )₂ 2 Cu ( CN )₂ 2 CuCN + CN - CN CuCN +3 KCN K ₃ [ Cu ( CN )₄ ] gathered

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