Chemical Kinetics - Order of Reaction and Reactants - Model Question

JEE Question 2007 Paper II

Consider a reaction aG+bH--> Products. When concentration of both the reactants G and H is doubled, the rate increases by eight times. However, when concentration of G is doubled keeping the concentration of H fixed, the rate is doubled. The overall order of the reaction is
(A) 0
(B) 1
(C) 2
(D) 3

Solution: D

This is a question of chapter chemical kinetics.
Reason: When G alone is doubled, rate is doubled. That is the exponent of [G] is one in rate law. When both are doubled, rate increases by 8 times, telling us that exponent of [H] is 2 in rate law. So overall order of reaction is sum of the two exponents that is 3.
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