Q13 / 160 · TS EAMCET 2024 (09 May Shift 1) · Chemistry

Assertion : $\mathrm{MgO}, \mathrm{CaO}, \mathrm{SrO}$ and BaO are insoluble in water. Reason (R) : In aqueous medium the basic strength of $\mathrm{MgO}, \mathrm{CaO}, \mathrm{SrO}$ and BaO increases with increase in the atomic number of metal. The correct option among the following is

  • A
    (A) and (R) are correct. (R) is the correct explanation of (A)
  • B
    (A) and (R) are correct, but (R) is not the correct explanation of (A)
  • C
    (A) is correct but (R) is not correct
  • Correct answer
    D
    (A) is not correct but (R) is correct

Solution

The solubility of an ionic compound like $\mathrm{MgO}, \mathrm{CaO}$, SrO and Bao in water depends on the strength of the ionic bonds between the cation and the anion in the compound. So Assertion is wrong. On the other hand, on going down the group in alkaline earth metals, as the atomic size increases, the reactivity increases, hence on going down the group, the basic strength of oxides also increases. $\mathrm{BeO} \lt \mathrm{MgO} \lt \mathrm{CaO} \lt \mathrm{SrO} \lt \mathrm{BaO}$ Reason is correct.

Hence, the correct answer is option: 'D'.

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