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Chemistry · 2026 · 2 marks
CBSE 2026 · Region 2 · Set 1 · Q18
(a) Define activation energy. 1 + 1 (b) Write the unit of rate constant for (i) zero order reaction, (ii) second order reaction.
(a)
Define activation energy. $\displaystyle 1$ + $\displaystyle 1$
(b)
Write the unit of rate constant for
(i)
zero order reaction, (ii) second order reaction.
Marking-scheme solution
(a)
The energy required by the reactants to form the activated complex is called
activation energy. / The minimum amount of energy required by the reactants
to cross the energy barrier to form products.
(b)(i)
mol L−$\displaystyle 1$ s−$\displaystyle 1$
(ii)
mol−$\displaystyle 1$ L s−$\displaystyle 1$
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CBSE Class 12 Chemistry past-paper question from the 2026 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.