The formula X + ZY → XZ + Y shows that O A. X and Y bonded into a more complex molecule.
O B. ZY has decomposed into two smaller compounds.
O C. X is a more reactive compound than Y.
O D. Y has changed into a new compound.

i think its 100

i hope this !

d

explanation:

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