Chemistry Class 12 NCERT Solutions: Chapter 4 Chemical-Kinetic Part 7

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Q: 12. The reaction between A and B is first order with respect to and zero order with respect to B. Fill in the blanks in the following table:

Q_12_Table the Reaction Between a and B Is First Order With Respect to a and Zero Order With Respect to B
Q_12_Table the Reaction Between A and B is First Order with Respect to A and Zero Order with Respect to B


Initial rate








The given reaction is of the first order with respect to A and of zero order with respect to B.

Therefore, the rate of the reaction is given by,

⇒ Rate = k [A]

From experiment I, we obtain

From experiment II, we obtain

From experiment III, we obtain

From experiment IV, we obtain

Q: 13. Calculate the half-life of a first order reaction from their rate constants given below: (i)




(i) Half-life,

(ii) Half-life,

(iii) Half-life,

Q: 14. The half-life for radioactive decay of is years. An archaeological artifact containing wood had only of the found in a living tree. Estimate the age of the sample.



It is known that,

Hence, the age of the sample is years