VMMC VMMC Medical Solved Paper-2006

  • question_answer
    In the first order reaction, the concentration of the reactants is reduced to 25% in one hour. The half life period of the reaction is:

    A)  2hr                                       

    B)         4hr                       

    C)         1/2 hr                                  

    D)         1/4 hr

    Correct Answer: C

    Solution :

    For first order reaction, \[k=\frac{2.303}{{{t}_{1/2}}}\log \frac{a}{\left( a-\frac{a}{2} \right)}=\frac{2.303}{t}\log \frac{a}{(a-x)}\] \[\therefore \]  \[\frac{2.303}{{{t}_{1/2}}}\log 2=\frac{2.303}{1}\log \frac{a}{a/4}\] \[\frac{2.303\times 0.3010}{{{t}_{1/2}}}=2.303\times \log 4\] \[\therefore \]                  \[{{t}_{1/2}}=\frac{0.3010}{\log 4}\]                                 \[=\frac{0.3010}{0.6020}\] \[=\frac{1}{2}\,\text{hour}\]


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