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Question
For a first order reaction, the half-life period (t1/2) is ______.
Options
proportional to the initial concentration.
inversely proportional to the initial concentration.
proportional to the square root of the initial concentration.
independent of the initial concentration.
Solution
For a first order reaction, the half-life period (t1/2) is independent of the initial concentration.
Explanation:
For a first-order reaction, the half-life period is constant. The half-life of a reaction is the time in which the concentration of a reactant is reduced to one-half of its initial concentration. It is represented as (t1/2).
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A plant or any other living being maintains a reasonable balance of C-14 (radioactive carbon) in its tissue during its lifetime. C-14 is used to determine the age of fossils. In the upper atmosphere, neutrons present in the cosmic rays are captured to produce the following nuclear reaction. \[\ce{_7N^14 + _0n^1 -> _6C^14 + _1H^1}\] C-14 isotope circulates in the atmosphere and is absorbed by living organisms during photosynthesis. The ratio of C-14 to C-12 in living beings is 1 : 1012. Once a living being dies, the level of C-14 in the dead being decreases due to the following reaction. \[\ce{_6C^14 -> _7N^14 + _-1e^0 + γ rays}\] The death of the plant brings an end to its tendency to take up C-14. The half-life period of C-14 is 5770 years. By knowing the concentration of C-14 in the living plant and the piece of dead material at a particular time, the age of the material (fossil) can be determined. |
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