Import Question JSON

Current Question (ID: 8693)

Question:

$\text{H}_2\text{O}_2 \text{ restores the colour of old lead paintings by:}$

Options:

1. $\text{Converting } \text{PbO}_2 \text{ to } \text{Pb}$
2. $\text{Oxidising } \text{PbS} \text{ to } \text{PbSO}_4$
3. $\text{Converting } \text{PbCO}_3 \text{ to } \text{Pb}$
4. $\text{Oxidizing } \text{PbSO}_3 \text{ to } \text{PbSO}_4$

Solution:

$\text{Hint: Old painting gets black due to the formation of lead oxide.}$ $\text{Explanation:}$ $\text{When the old oil paintings are kept in the atmosphere for a long period, the traces of gas present in the atmosphere converts lead oxide } (\text{PbO}) \text{ into lead sulphide } (\text{PbS}) \text{ which is black in colour.}$ $\text{Therefore, these paintings get tarnished. The original whiteness can be restored by keeping them in hydrogen peroxide solution for some time as a result of which lead sulphide is oxidised to lead sulphate.}$ $\text{The reaction is as follows:}$ $\text{PbS} + 4\text{H}_2\text{O}_2 \rightarrow \text{PbSO}_4 + 4\text{H}_2\text{O}$ $\text{Black} \rightarrow \text{White}$ $\text{The black lead sulphide } (\text{PbS}) \text{ is oxidized by hydrogen peroxide to form white lead sulphate } (\text{PbSO}_4)\text{, thus restoring the original white colour of the painting.}$

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
}