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Current Question (ID: 8292)

Question:
$\text{The work done in ergs for the reversible expansion of one mole of an ideal gas from a volume of 10 liters to 20 liters at } 25^{\circ}\text{C is -}$
Options:
  • 1. $-2.303 \times 298 \times 0.082 \log 2$
  • 2. $-298 \times 10^7 \times 8.31 \times 2.303 \log 2$
  • 3. $2.303 \times 298 \times 0.082 \log 0.5$
  • 4. $-8.31 \times 10^7 \times 298 - 2.303 \log 0.5$
Solution:
$\text{Hint: } W = -2.303 \text{ nRT}\log \frac{V_2}{V_1}$ $\text{Step 1: Identify the given values}$ $\text{The given values are as follows:}$ $V_1 = 10 \text{ L (initial volume)}$ $V_2 = 20 \text{ L (final volume)}$ $n = 1 \text{ mol (number of moles)}$ $T = 25^{\circ}\text{C} = 273 + 25 = 298 \text{ K (temperature)}$ $R = 8.314 \text{ J mol}^{-1}\text{K}^{-1} \text{ (gas constant)}$ $\text{Conversion factor: } 1 \text{ J} = 10^7 \text{ erg}$ $\text{Therefore, } R = 8.314 \times 10^7 \text{ erg mol}^{-1}\text{K}^{-1}$ $\text{Step 2: Apply the formula for work done in reversible isothermal expansion}$ $\text{For a reversible isothermal expansion of an ideal gas, the work done is given by:}$ $W = -nRT\ln\frac{V_2}{V_1}$ $\text{Using base-10 logarithm: } W = -2.303 \times nRT\log\frac{V_2}{V_1}$ $W = -2.303 \times 1 \times 8.314 \times 10^7 \times 298 \times \log\frac{20}{10}$ $W = -2.303 \times 8.314 \times 10^7 \times 298 \times \log 2$ $\text{Rearranging: } W = -298 \times 10^7 \times 8.314 \times 2.303 \times \log 2$ $\text{Step 3: Verify the answer}$ $\text{The negative sign indicates that the gas is doing work on the surroundings during expansion.}$ $\text{The answer matches option 2: } -298 \times 10^7 \times 8.31 \times 2.303 \log 2$ $\text{Note: There's a slight difference in the value of R (8.31 vs. 8.314), but this is within acceptable rounding for multiple-choice options.}$

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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
}