When a substance changes its state, all but one of these statements is true. that is
a) mass remains constant.
b) only the form changes.
c) kinetic energy changes.
d) something new is formed.

The answer is D, because a ,b ,and c are all true, and the question is asking for the one that is false

D .  Something new is formed.

Explanation:

The option A, B and C are true statement while D is false statement.

Mass remains constant.

During a physical change mass remain constant, just state change.

Only the form changes.

During a physical change ,just state change

Kinetic energy changes.

During a physical change ,kinetic energy also change because liquid, solid and gases have different inter molecular forces which relate to K.E.

Something new is formed.

when substance change state, then it remained as such as before, just its state change, not composition.