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Current Question (ID: 18685)

Question:

$\text{Aqueous copper sulphate solution gives a green precipitate of A with aqueous potassium fluoride. What would be the correct molecular formula of A?}$

Options:

1. $[\text{CuF}_6]^{3-}$
2. $[\text{CuF}_4]^{2-}$
3. $[\text{CuF}_2]^{-}$
4. $[\text{CuF}_5]^{4-}$

Solution:

$\text{HINT: Cu}^{2+} \text{ ion form tetrahedral complex with fluoride ion}$ $\text{In an aqueous solution, CuSO}_4 \text{ exists as } [\text{Cu(H}_2\text{O)}_4]\text{SO}_4.$ $\text{It is blue in color due to the presence of } [\text{Cu(H}_2\text{O)}_4]^{2+}.$ $\text{When KF is added following reaction will take place:}$ $[\text{Cu(H}_2\text{O)}_4]^{2+} + 4\text{F}^- \rightarrow [\text{CuF}_4]^{2-} + 4\text{H}_2\text{O}$ $\text{(A) Green}$ $\text{The green color of the solution is due to the formation of } [\text{CuF}_4]^{2-} \text{ ion.}$

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
}