Properties of Carbon Allotropes Steps:

• Examine structures: diamond is a 3D tetrahedral lattice, graphite is 2D hexagonal layers, fullerene (C60) is a discrete spherical molecule.
• Evaluate statement 1: all feature covalent bonds between carbon atoms—true for diamond (sigma), graphite (sigma and pi), and fullerene (sigma and pi).
• Evaluate statement 2: diamond and graphite are giant covalent lattices, but fullerene consists of finite C60 molecules—not giant.
• Evaluate statement 3: graphite and fullerene have delocalized pi electrons, but diamond has only localized sigma bonds—no delocalization.

Why D is correct:

• D selects only statement 1, matching the definition of covalent bonding in allotropes while excluding inaccuracies in giant structure (statement 2) and electron delocalization (statement 3).

Why the others are wrong:

• A includes all three, but 2 and 3 fail for fullerene and diamond.
• B includes 1 and 2, but 2 fails as fullerene is molecular.
• C includes 1 and 3, but 3 fails as diamond lacks delocalization.

Final answer: D