Which reaction can be used to calculate the enthalpy of formation of a substance? CO2 (g)→CO (g)+12O2 (g)

CO (g)+12O2 (g)→CO2 (g)

H2 (g)+12O2 (g)→H2O (l)

NO (g)+O2 (g)→NO3 (g)

answer; i believe that the correct answer is (c) explore the outer planets; / plz check good luck

answer : third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol

explanation :

let us write down the given equations

equation 1 :

equation 2 :

equation 3 :

let us use hess's law to find out which 2 equations can be added to get the third equation.

let us reverse equation 2 and multiply it by 2. the new equation that we get is,

equation 4 :

let us add equation 1 & 4

the above equation is similar to equation 3 but has different value for dhrxn.

therefore third trial had the contaminated sample and the correct value for dhrxn should be 1000 kj/mol