A first-order reaction is 50% completed in 1.26 × 1014 s. How much time would it take for 100% completion?

(i) 1.26 × 10¹⁵ s

(ii) 2.52 × 10¹⁴ s

(iii) 2.52 × 10²⁸ s

(iv) infinite

Correct Answer: (iv) infinite

Explanation: The time taken for the 100% completion of the reaction is infinite.