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Current Question (ID: 18679)

Question:

$\text{The species that are colourless:}$ $\text{(Z of Ti = 22, Co = 27, Cu = 29, Ni = 28)}$

Options:

1. $\text{TiF}_6^{2-} \text{ and CoF}_6^{3-}$
2. $\text{Cu}_2\text{Cl}_2 \text{ and NiCl}_4^{2-}$
3. $\text{TiF}_6^{2-} \text{ and Cu}_2\text{Cl}_2$
4. $\text{CoF}_6^{3-} \text{ and NiCl}_4^{2-}$

Solution:

$\text{HINT: The species which cannot show d-d transition due to no unpaired electrons are colorless.}$ $\text{Explanation:}$ $\text{(a) Ti is present as Ti}^{4+} \text{ in TiF}_6^{2-}$ $\text{Hence, Ti}^{4+} = [\text{Ar}] \ 3d^0 \ 4s^0$ $\text{(c) Cu is present as Cu}^{+} \text{ in Cu}_2\text{Cl}_2$ $\text{Cu}^{+} = [\text{Ar}] \ 3d^{10} \ 4s$ $\text{As there is no unpaired electron present, therefore Cu}_2\text{Cl}_2 \text{ is colourless.}$ $\text{(d) Ni is present as Ni}^{2+} \text{ in NiCl}_4^{2-}$ $\text{Ni}^{2+} = [\text{Ar}] \ 3d^8 \ 4s$ $\text{Since unpaired electrons are present, hence coloured.}$ $\text{So, TiF}_6^{2-} \text{ and Cu}_2\text{Cl}_2 \text{ are colourless species.}$

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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
}