Answer:
Substances which are non heat-resistant and volatile organic liquid with flammable vapor.
Step-by-step explanation:
Bunsen Burner are used as a source of fire in the laboratory for heating up substances. Extra care however should be taken during heating in order to prevent fire or other forms of accidents.
Heating of mind heat resistant substances should be frowned at as the substances may get heated up and melt thereby exposing the liquid substances which may be flammable to fire thereby causing fire outbreak.
Heating of volatile organic liquid with flammable vapor should also be discouraged to prevent fire accidents.