Question

identify the combustible substance from the following options that reacts with oxygen to generate heat.
a iron nail
b stone piece
c glass
d wood

Explanation:

Combustible substances are those that can burn in the presence of oxygen. Iron nail (a) rusts (a slow reaction with oxygen, not combustion). Stone piece (b) and glass (c) are non - combustible. Wood (d) is a combustible substance as it can react with oxygen (burn) to generate heat.

Answer:

d. wood