One gram of ⁹⁰ Sr gets converted to 0.953 g after 2 years. The half life of ⁹⁰ Sr, and the amount of ⁹⁰ Sr… · ABC26PH0473
Subject: Physical Chemistry · Chapter: Chemical Kinetics · Topic: Chemical Kinetics – General · Exam: GATE 2005-2021 · Marks: 2 · Difficulty: Medium
One gram of ${ }^{90} \mathrm{Sr}$ gets converted to 0.953 g after 2 years. The half life of ${ }^{90} \mathrm{Sr}$, and the amount of ${ }^{90} \mathrm{Sr}$ remaining after 5 years are
(a)1.44 years and 0.916g
(b)57.6 years and 0.75 g
(c)28.8 years and 0.887 g
(d)100 ears and 0.982 g
Answer
Answer: C ✓ checked by 4AB · confidence high
Explanation
k = ln(1/0.953)/2 = 0.0241 yr⁻¹, t½ = 28.8 yr; after 5 yr, e^(−0.120) = 0.887 g (c).