The free energy of formation of NO is 78 kJ `mol^(-1)` at the temperature of an automobile engine (1000 K). What is the equilibrium constant for this reaction at 1000 K
`(1)/(2)N_(2)(g)+(1)/(2)O_(2)(g)iffNO(g)`
A. `8.4xx10^(-5)`
B. `7.1xx10^(-19)`
C. `4.2xx10^(-10)`
D. `1.7xx10^(-19)`