It is a change which alters the chemical properties of a substance or which forms a new substance.
(It; is; a change which alters the chemical properties of a substance or which forms a new substance) (a change; alters; the chemical properties of a substance) (a change; forms; a new substance)
It a change a change
is alters forms
a change which alters the chemical properties of a substance or which forms a new substance
the chemical properties of a substance
a new substance