In chemistry, an indicator is a substance that undergoes an easily observable change in property (usually color) under certain chemical conditions.
(an indicator; is; a substance that undergoes an easily observable change in property (usually color) under certain chemical conditions; L:In chemistry) (a substance; undergoes; an easily observable change in property (usually color) under certain chemical conditions)
an indicator a substance
is undergoes
a substance that undergoes an easily observable change in property (usually color) under certain chemical conditions L:In chemistry
an easily observable change in property (usually color) under certain chemical conditions