The answer is D (3 only).
• Statement 1 is incorrect: a longer covalent bond means the shared pair is further from the nuclei, so the attraction is weaker and the bond energy is generally smaller, not greater.
• Statement 2 is incorrect: a larger nuclear charge does not always give a stronger bond. I in HI has a larger nuclear charge than Cl in HCl, yet the H-I bond energy is lower than the H-Cl bond energy, because the I atom is much larger and the bond is longer.
• Statement 3 is correct: bond energy is the energy needed to overcome the attraction between the shared pair of electrons and the nuclei of the bonded atoms, so a greater attraction always means a greater bond energy.
Only statement 3 is always correct.
• A is wrong: it includes statement 1, which is incorrect.
• B is wrong: statement 1 is incorrect, and it leaves out statement 3, which is correct.
• C is wrong: it includes statement 2, which is not always correct.
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