Import Question JSON

Current Question (ID: 9117)

Question:

$\text{Property of the alkaline earth metals that increases with their atomic number is -}$

Options:

1. $\text{Solubility of their hydroxides in water.}$
2. $\text{Solubility of their sulphates in water.}$
3. $\text{Ionisation energy.}$
4. $\text{Electronegativity.}$

Solution:

$\text{HINT: Solubility of alkaline earth metal hydroxides increases down the group.}$ $\text{Explanation:}$ $\text{STEP 1: Electronegativity as well as ionisation energy both usually decrease on moving downward a group with increase in atomic number.}$ $\text{STEP 2: The hydroxides and sulphates of alkaline earth metals are ionic solids and the solubility of ionic solids is governed by two factor, viz, lattice energy and hydration energy.}$ $\text{For solubility, hydration energy > lattice energy.}$ $\text{Hydration energy varies inversely with size, ie, decreases with increase in size.}$ $\text{STEP 3: However, lattice energy incase of sulphates, remains almost same with increase in the atomic number of alkaline earth metals, due to large size of sulphate ion.}$ $\text{Hence, hydration energy only governs the solubility in this case. Thus, solubility of alkaline earth metal sulphates decreases as the hydration energy decreases on moving downward the IIA group.}$ $\text{STEP 4: On the other hand, in case of hydroxides, the lattice energies are different because of medium size of hydroxide ions and decreases on moving from Be to Ba.}$ $\text{This tends to increase the solubility and to overcome the counter-effect produced by the decrease in hydration energy.}$ $\text{Hence, the solubility of alkaline earth metal hydroxides increases with increase in the atomic number of alkaline earth metals.}$

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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
}