# NEET Chemistry Chemical Kinetics Questions Solved

Assertion : A lump of coal burns at a moderate rate in air while coal dust burns explosively.

Reason : Coal dust contains very fine particles of carbon.

(A). A lump of coal burns at a moderate rate in air while coal dust burns explosively because coal dust contains very fine particles of carbon. So, for a certain mass, the surface area a coal dust is very large as compared to that of the lump coal. The increases surface area permits a close contact with the oxidiser oxygen gas (in the air) and therefore coal dust burns at a very high rate leading to an explosion. In the case of lump coal, the surface available for reaction is small. So, it burns slowly at moderate rate in air.

Difficulty Level:

• 63%
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