Import Question JSON

Current Question (ID: 18858)

Question:

$\text{Which of the following is a coloured and paramagnetic compound?}$

Options:

1. $\text{CuF}_2$
2. $\text{K}_2\text{Cr}_2\text{O}_7$
3. $\text{KMnO}_4$
4. $\text{K}_4[\text{Fe(CN)}_6]$

Solution:

$\text{Hint: CuF}_2 \text{ is coloured and paramagnetic.}$ $\text{Explanation:}$ $\text{Generally, transition elements show colour due to d-d transition. For d-d transition, unpaired electron should be present.}$ $\text{Other reasons also exist for the colour of compounds, like MLCT, LMCT, etc.}$ $\begin{array}{|c|c|c|c|} \hline \text{Compound} & \text{Metal ion} & \text{Electronic configuration} & \text{Unpaired electron} \\ \hline \text{CuF}_2 & \text{Cu}^{+2} & d^9 & 1 \\ \text{K}_2\text{Cr}_2\text{O}_7 & \text{Cr}^{+6} & d^0 & 0 \\ \text{KMnO}_4 & \text{Mn}^{+7} & d^0 & 0 \\ \text{K}_4[\text{Fe(CN)}_6] & \text{Fe}^{+2} & d^6(\text{Low spin}) & 0 \\ \hline \end{array}$ $\text{Hence, CuF}_2 \text{ is coloured and paramagnetic.}$ $\text{Other compounds are also coloured but not paramagnetic.}$

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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
}