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The s-Block Elements

Multiple Choice Questions

441.

Which of the following has highest hydration energy?

MgCl₂
CaCl₂
BaCl₂
SrCl₂

442.

Addition of sodium thiosulphate solution to a solution of silver nitrate gives X as white precipitate, insoluble in water but soluble in excess thiosulphate solution to give Y. On boiling in water, Y gives Z. X, Y and Z respectively are

Ag₂S₂O₃, Na₃[Ag(S₂O₃)₂], Ag₂S
Ag₂SO₄, Na[Ag(S₂O₃)₂], Ag₂S₂
Ag₂S₂O₃, Na₅[Ag(S₂O₃)₃], AgS
Ag₂SO₃, Na₃[Ag(S₂O₃)₂], Ag₂O

443.
The aqueous solution of which of the following salt will have the lowest pH ?

NaClO₃

NaClO

NaClO₄

NaClO₂

NaClO₄

${NaClO}_{4} \to {Na}^{+} + {ClO}_{_{4}}^{-} {NaClO}_{3} \to {Na}^{+} + {ClO}_{3}^{-} {NaClO}_{2} \to {Na}^{+} + {ClO}_{2}^{-} NaClO \to {Na}^{+} + {ClO}^{-}$

ln aqueous solution, these compounds decompose into ions. ClO₄^- will most easily abstract proton from water molecules. So it will be most acidic.

444.

Assertion : Na₂SO₄ is soluble in water while BaSO₄ is not.

Reason : Lattice energy of BaSO₄ exceeds its hydration energy.

If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
If Assertion is true but Reason is false.
If Assertion is false but Reason is true.