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STD 12 - 3. Chemical kinetics — JEE STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceJEESTD 12 - 3. Chemical kinetics4 Marks
MCQ
A Substance undergoes first order decomposition. The decomposition follows two parallel first order reactions asThe percentage distribution of $B$ and $C$  are

$A\,\xrightarrow{{{k_1}}}B$        ${k_1}\, = \,1.26\, \times \,{10^{ - 4}}\,{S^{ - 1}}$

$A\,\xrightarrow{{{k_2}}}C$       ${k_2}\, = \,3.8\, \times \,{10^{ - 5}}\,{S^{ - 1}}$

  • A
    $75\% $ $B $ and $ 25\%$ $ C$
  • B
    $80\%$ $B $ and $20\%$ $C$
  • C
    $60\% $ $B$  and $40\%$ $ C$
  • ✓
    $76.83\%$ $ B$ and $23.17\%$ $C$
✓

Answer

Correct option: D.
$76.83\%$ $ B$ and $23.17\%$ $C$
d
$\% $ distribution of $B = \frac{{{K_1}}}{{{K_1} + {K_2}}} \times 100$

$ = \frac{{1.26 \times {{10}^{ - 4}}}}{{1.26 \times {{10}^{ - 4}} + 3.8 \times {{10}^{ - 4}}}} \times 100$

$B\% = 76.83\% $

$\% $ Distribution of  $C = \frac{{{K_2}}}{{{K_1} + {K_2}}} \times 100$

$ = \frac{{3.8 \times {{10}^{ - 4}}}}{{1.26 \times {{10}^{ - 4}} + 3.8 \times {{10}^{ - 4}}}} \times 100$

$C\% = 23.17\% $

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