Q. Consider the reaction, When concentration of alone was doubled, the half-life did not change. When the concentration of alone was doubled, the rate increased by two times. The unit of rate constant for this reaction is

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Solution:

Products
When conc. of B is doubled, the half life did not change, hence reaction is of first order w.r.t. B. When concentration of A is doubled, reaction rate is
Hence over all order of reaction is
So, unit of rate constant
Hence, (1) is correct.