Sujit was performing an experiment in the laboratory. He collected four substances I, II, III, and IV and kept all of them in contact with air at room temperature. He observed that substance III suddenly bursts into flames. Then, he heated I, II, and IV and found out that while I and II catch fire, substance IV does not. However, substance IV catches fire on prolonged heating. Which substance undergoes spontaneous combustion in Sujit's experiment?

Sujit was performing an experiment in the laboratory. He collected fou

1.	Sujit was performing an experiment in the laboratory. He collected four substances I, II, III, and IV and kept all of them in contact with air at room temperature. He observed that substance III suddenly bursts into flames. Then, he heated I, II, and IV and found out that while I and II catch fire, substance IV does not. However, substance IV catches fire on prolonged heating. Which substance undergoes spontaneous combustion in Sujit's experiment?
A.	I
B.	II
C.	III
D.	IV
Answer» D. IV