Which of the following changes when a catalyst is used

Enthalpy of reaction

activation energy

both enthalpy of reaction and activation energy change

neither enthalpy of reaction nor activation change

In which situation can a mixture always be called a solution

Ineed to find the answer of this question because i dont understand it

Consider the following multistep reaction: a b→ab(slow) a ab→a2b(fast)−−−−−−−−−−−−−−−−− 2a b→a2b(overall) based on this mechanism, determine the rate law for the overall reaction. express your answer in standard masteringchemistry format. for example, if the rate law is k[a]3[b]2 type k*[a]^3*[b]^2