Using the following data, calculate the standard heat of formation (( Δ Hf° )) in kJ/mol:

[ Δ H = 242.3 , kJ ]
[ Δ H = 151.0 , kJ ]
[ Δ H = 211.3 , kJ ]
[ Δ H = 62.8 , kJ ]

a) ( Δ Hf° = 46.8 , kJ/mol )
b) ( Δ Hf° = 665.4 , kJ/mol )
c) ( Δ Hf° = -665.4 , kJ/mol )
d) ( Δ Hf° = -46.8 , kJ/mol )