Which of the statements below is not a correct part of collision theory?

a. reactant molecules must have some minimum amount of energy to react.
b. every time reactant molecules collide, a reaction occurs.
c. the orientation of reactant molecules has an effect on the outcome of the reaction.

b. Every time reactant molecules collide, a reaction occurs.  

Explanation:

Each gas molecule undergoes about  10¹⁰ collisions per second. If a reaction occurred every time there was a collision, the reaction would be finished almost instantaneously.

a. and c. are wrong. They are parts of collision theory.

the enthalpy of formation of water is given as -285.8kj/mol, which states that the enthalpy of formation is negative.

negative enthalpy of formation indicates that the heat is released during the reaction process. the heat is released from reaction to the surroundings the enthalpy is expressed with a negative sign with the energy given out in the reaction process.

the formation of water takes place by giving out heat which is -285.8 kj/mol.