Question

Which of these changes do not involve forming or breaking chemical bonds?

Answer 1

Hi 
let me help you you out 

the answer is boiling ans melting 

everything else can form or break chemical bonds 

hope it helps 

Answer 2

When bonds form or break, it is called a chemical change. Which changes the substance completely and it cannot go back to the original substance. 
Therefore, to answer this question correctly, we must find a physical property. Which can be a change in state and doesn't change the substance by breaking bonds or forming new bonds. 
D. Boiling and melting
Explanation:
Because when you melt, you change the physical state. Also when you boil something, you are not changing the bonds. That is because you can change it back to its original substance. It is a temperature change which makes it melt or boil. 
Hope I helped. :)