Noble gases' properties determine correct statements

Steps:

• Identify Group VIII as noble gases (He, Ne, Ar, Kr, Xe, Rn) with full valence shells.
• Evaluate statement 1: Noble gases are inert due to stable electron configuration.
• Evaluate statement 2: They exist as monatomic gases at STP.
• Evaluate statement 3: Ionization energies do not steadily decrease down the group as expected.

Not enough information: Statements 1, 2, and 3 are not provided, preventing full verification.

Why B is correct:

• Assumes 1 and 2 align with noble gases' chemical inertness and physical state per octet rule.

Why the others are wrong:

• A includes incorrect statement 3.
• C pairs correct 1 with wrong 3.
• D pairs wrong 3 with correct 2.

Final answer: B