Leaching of gold with dilute aqueous solution of NaCN in presence of oxygen gives complex [A], which on reaction with zinc forms the elemental gold and another complex [B]. [A] and [B], respectively are :
- \([Au(CN)_4]^–\) and \([Zn(CN)_2 (OH)_2]^{2-}\)
- \([Au(CN)_2]^–\) and \([Zn (OH)_4]^{2-}\)
- \([Au(CN)_2]^–\) and \([Zn (CN)_4]^{2-}\)
- \([Au(CN)_4]^{2-}\) and \([Zn (CN)_6]^{4-}\)
The Correct Option is C
Solution and Explanation
In the metallurgy of gold
\(4Au + 8CN^– + 2H_2O + O_2 → 4[Au(CN)_2]^– + 4OH^–\)
\(2[Au(CN)_2]^– + Zn → [Zn(CN)_4]^{2–} + 2Au\)
So, the correct option is (C): \([Au(CN)_2]^–\) and \([Zn (CN)_4]^{2-}\)
Top Questions on Concentration of ores
- Which of the following are carbonate ores?
I. Siderite
II. Kaolinite
III. Calamine
IV. Sphalerite- AP EAPCET - 2025
- Chemistry
- Concentration of ores
- Identify the sulphide ore among the following:
- TS POLYCET - 2025
- Chemistry
- Concentration of ores
- Which of the following methods is used for the concentration of ore?
- TS POLYCET - 2025
- Chemistry
- Concentration of ores
- Pyrolusite ore is:
- BCECE Nursing - 2024
- Chemistry
- Concentration of ores
- A → P is a zero-order reaction. At 298 K, the rate constant of the reaction is \( 1 \times 10^{-3} \) mol L\(^{-1}\) s\(^{-1}\). Initial concentration of 'A' is 0.1 mol L\(^{-1}\). What is the concentration of 'A' after 10 sec?
- AP EAMCET - 2024
- Chemistry
- Concentration of ores
Questions Asked in JEE Main exam
- The mass of magnesium required to produce 220 mL of hydrogen gas at STP on reaction with excess of dilute HCl is: (Given molar mass of Mg = 24 g/mol)
- JEE Main - 2025
- Gas laws
- A force of 49 N acts tangentially at the highest point of a sphere (solid of mass 20 kg) kept on a rough horizontal plane. If the sphere rolls without slipping, then the acceleration of the center of the sphere is:
- JEE Main - 2025
- Quantum Mechanics
- Suppose that the number of terms in an A.P. is \( 2k, k \in \mathbb{N} \). If the sum of all odd terms of the A.P. is 40, the sum of all even terms is 55, and the last term of the A.P. exceeds the first term by 27, then \( k \) is equal to:
- JEE Main - 2025
- Arithmetic Progression
- The value of \( (\sin 70^\circ)(\cot 10^\circ \cot 70^\circ - 1) \) is:
- JEE Main - 2025
- Trigonometric Identities
Let \( A = \{-3, -2, -1, 0, 1, 2, 3\} \). A relation \( R \) is defined such that \( xRy \) if \( y = \max(x, 1) \). The number of elements required to make it reflexive is \( l \), the number of elements required to make it symmetric is \( m \), and the number of elements in the relation \( R \) is \( n \). Then the value of \( l + m + n \) is equal to:
- JEE Main - 2025
- Sets and Relations
Concepts Used:
General Principles and Processes of Isolation of Elements
What are Ores and Minerals?
Minerals are the naturally occurring, homogeneous inorganic solid substances. They are having a definite chemical composition and crystalline structure, hardness and color. For example, copper pyrite, calamine, etc.
Impurities in an ore are called gauge. The removal of a gauge from the ore is called concentration ore.
Several steps are involved in the extraction of pure metal from ores. Major steps are as follows –
- Concentration of the ore
- Isolation of the metal from its concentrated ore
- Purification of the metal