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Which of the following statements is correct?

1. Ionic solids are unstable because the sum of ionization enthalpy and electron gain enthalpy is positive.
2. The van der Waals radius represents the effective size of an atom in a non-bonded situation, i.e., in the absence of a chemical bond.
3. The energy required to break the two O-H bonds in water is not the same for both bonds.
4. According to VSEPR theory, multiple bond electron pairs (two or three pairs in a double or triple bond) are treated as a single super pair.

Correct answer: According to VSEPR theory, multiple bond electron pairs (two or three pairs in a double or triple bond) are treated as a single super pair.

Solution

Option A is wrong: Ionic solids ARE stable because the large lattice energy (exothermic) more than compensates for the positive sum of ionization enthalpy and electron gain enthalpy. Option B is wrong: Van der Waals radius represents the effective size of an atom in a non-bonded environment (not bonded). Option C is wrong: the two O-H bonds in H2O ARE broken with different energies (first bond easier than second, because after first H is removed the anion holds remaining H more tightly — actually enthalpy of first dissociation differs from second). Option D is correct: VSEPR treats a multiple bond as a single super pair (one domain) for determining geometry.

Related JEE Advanced Chemistry questions

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