Home › Previous year questions › GATE 2021 CY › Question 56GATE 2021 CY – Question 56 Physical Chemistry · Kinetics and Reaction Dynamics: Elementary, parallel, opposing, and consecutive reactions. Steady state approximation. Mechanism of complex reactions. Unimolecular reactions. Potential energy surface and classical trajectories, Concept of saddle points, Transition state theory: Eyring equation, thermodynamic aspects. Kinetics of polymerization. Catalysis concepts and enzyme catalysis. Kinetic isotope effects. Fast reaction kinetics: relaxation and flow methods. Diffusion controlled reactions. Kinetics of unimolecular and bimolecular photophysical processes, Quantum yield calculation, static and dynamic quenching. · 2 marks · Numerical answer
Initially there is 1 mg radioactive $\!{}^{60}_{27}Co$, half-life 5.27 years. The amount disintegrated in one year is ______ mg (two decimal places).
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Show answer and explanation Correct answer: 0.11 to 0.13
Explanation Radioactive decay gives m(t)=m0×2^(−t/t½). With m0=1 mg and t½=5.27 years, the remaining mass after one year is 2^(−1/5.27)≈0.8768 mg. The disintegrated amount is 1−0.8768≈0.1232 mg, hence **0.12 mg** to two decimals. The question asks for loss, not remaining mass.