Suppose a New Metallic Element X Is Discovered, and Its

Multiple Choice

Suppose a new metallic element X is discovered, and its reactions with oxygen gas and chlorine gas at 298 K are studied. However, it is later discovered that one of the samples was contaminated, and the ΔHº_rxn value from this trial is not reliable. Which trial had the contaminated sample, and what should the correct value of ΔHº_rxn be for this trial?

A) Trial 1 had the contaminated sample; its ΔHº_rxn value should be -900 kJ/mol.
B) Trial 2 had the contaminated sample; its ΔHº_rxn value should be +100 kJ/mol.
C) Trial 3 had the contaminated sample; its ΔHº_rxn value should be -1000 kJ/mol.
D) Trial 3 had the contaminated sample; its ΔHº_rxn value should be +1000 kJ/mol.
E) Not enough information is provided; all three trials must be redone.