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JEE Main levelSingle correct optionDifficulty 2 of 3sb069

Lithium is the strongest reducing agent among the alkali metals in aqueous solution (most negative ) even though it has the highest ionisation enthalpy in the group. This is because

  1. ALi has the lowest sublimation enthalpy in the group
  2. Bthe hydration enthalpy of the very small Li+ is so large that it outweighs the other energy terms
  3. CLi+ has the lowest hydration enthalpy in the group
  4. DLi has the lowest ionisation enthalpy among alkali metals

Answer: B

depends on sublimation, ionisation and hydration enthalpy. Li+ has the largest charge density and thus the most negative hydration enthalpy, which dominates and makes Li the best aqueous reducing agent. Statements about low ionisation or sublimation enthalpy are false for Li.
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