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Chemistry · 2025 · 2 marks
CBSE 2025 · Region 2 · Set 1 · Q18
Define the following terms: 2 × 1 (a) Pseudo first order reaction (b) Half-life period of reaction ( t_1 / 2)
Define the following terms : $\displaystyle \mathbf{2} \boldsymbol{\times} \mathbf{1}$
(a)
Pseudo first order reaction
(b)
Half-life period of reaction $\displaystyle \left(\mathrm{t}_{1 / 2}\right)$
Marking-scheme solution
(a)
The reaction that seems to be of higher order but under certain conditions is of first
order.
(b)
The time in which the concentration of a reactant is reduced to one half of its initial
concentration / The time in which half of the reaction is completed.
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CBSE Class 12 Chemistry past-paper question from the 2025 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.