Import Question JSON

Current Question (ID: 18526)

Question:

$\text{The extraction of gold and silver involves leaching with } \text{CN}^- \text{ ion. Silver is later recovered by:}$

Options:

1. $\text{Liquation}$
2. $\text{Distillation}$
3. $\text{Zone refining}$
4. $\text{Displacement with Zn}$

Solution:

$\text{HINT: Ag is recovered by displacement of Zn.}$ $\text{Explanation:}$ $\text{STEP 1: Leaching is a process in which water-soluble substances are washed out from the soil.}$ $\text{Extraction of gold and silver involves leaching with CN}^- \text{ ion. Silver is later recovered by distillation of Zn.}$ $\text{In the metallurgy of silver or gold, the respective metal is leached with a dilute solution of NaCN or KCN in the presence of air to obtain the metal in solution as complex. From the complex, metal is obtained later by replacement.}$ $\text{STEP 2: In general,}$ $4\text{M}(\text{s}) + 8\text{CN}^-(\text{aq}) + 2\text{H}_2\text{O} (\text{aq}) + \text{O}_2(\text{g}) \rightarrow 4[\text{M(CN)}_2]^-(\text{aq}) + 4\text{OH}^-(\text{aq})$ $2[\text{M(CN)}_2]^-(\text{aq}) + \text{Zn}(\text{s}) \rightarrow [\text{Zn(CN)}_4]^{2-}(\text{aq}) + 2\text{M}(\text{s})$ $\text{M = Ag or Au. This method is known as Mac-Arthur Forest cyanide process.}$

Import JSON File

Upload a JSON file containing LaTeX/MathJax formatted question, options, and solution.

Expected JSON Format:

{
  "question": "The mass of carbon present in 0.5 mole of $\\mathrm{K}_4[\\mathrm{Fe(CN)}_6]$ is:",
  "options": [
    {
      "id": 1,
      "text": "1.8 g"
    },
    {
      "id": 2,
      "text": "18 g"
    },
    {
      "id": 3,
      "text": "3.6 g"
    },
    {
      "id": 4,
      "text": "36 g"
    }
  ],
  "solution": "\\begin{align}\n&\\text{Hint: Mole concept}\\\\\n&1 \\text{ mole of } \\mathrm{K}_4[\\mathrm{Fe(CN)}_6] = 6 \\text{ moles of carbon atom}\\\\\n&0.5 \\text{ mole of } \\mathrm{K}_4[\\mathrm{Fe(CN)}_6] = 6 \\times 0.5 \\text{ mol} = 3 \\text{ mol}\\\\\n&1 \\text{ mol of carbon} = 12 \\text{ g}\\\\\n&3 \\text{ mol carbon} = 12 \\times 3 = 36 \\text{ g}\\\\\n&\\text{Hence, 36 g mass of carbon present in 0.5 mole of } \\mathrm{K}_4[\\mathrm{Fe(CN)}_6].\n\\end{align}",
  "correct_answer": 4
}