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Current Question (ID: 21539)

Question:

$\text{Which of the following explains the primary cause of lanthanoid contraction?}$

Options:

1. $\text{Greater shielding of 5d electrons by 4f electrons.}$
2. $\text{Poor shielding of 5d electrons by 4f electrons.}$
3. $\text{Effective shielding of one of the 4f electrons by another in the sub-shell.}$
4. $\text{Poor shielding of one 4f electron by another within the sub-shell.}$

Solution:

$\text{Hint: poor shielding of fourteen f orbitals electrons}$ $\text{The radius of elements of the 4d-series is about the same as elements of the 5d series. This is due to the lanthanoid contraction.}$ $\text{This contraction is due to the imperfect shielding of one electron by another in the same sub-shell.}$ $\text{However, the shielding of one 4f electron by another is less than one d electron by another with the increase in nuclear charge along with the series.}$ $\text{There is a fairly regular decrease in the sizes with increasing atomic numbers.}$

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
}