A 3540-G Sample of an Unknown Metal M Is Burned in in the Presence

question 110

Multiple Choice

A 3.540-g sample of an unknown metal M is burned in the presence of excess oxygen,producing the oxide M₂O₃(s) and liberating 18.56 kJ of heat at constant pressure.What is the identity of the metal?
4M(s) + 3O₂(g) → 2M₂O₃(s)
Substance
ΔH°_f (kJ/mol)
Yb₂O₃(s)
-1814.6
Tb₂O₃(s)
-1865.2
Sm₂O₃(s)
-1823.0
Sc₂O₃(s)
-1908.8
Y₂O₃(s)
-1905.3

• A)Sm
• B)Yb
• C)Y
• D)Sc
• E)Tb

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