JEE Mains · Chemistry · STD 12 - 3. Chemical kinetics
The half-life of \({}^{65}Zn\) is 245 days. After x days, 75% of original activity remained. The value of x in days is _________ . (Nearest integer)
(Given \(: \log 3=0.4771\) and \(\log 2=0.3010\) )
- A 102
- B 122
- C 245
- D 61
Answer & Solution
Correct Answer
(A) 102
Step-by-step Solution
Detailed explanation
\(t _{1 / 2}=\frac{\ell n 2}{K}\) \(K =\frac{\ell n 2}{245}\) \(t =\frac{1}{K} \ell n \frac{ a _0}{ a _{ t }}\) \(t_{25 \%}=\frac{1}{K} \ell n \frac{4}{3}\) \(t _{25 \%}=\frac{1}{\frac{\ell n 2}{245}} \ell n \frac{4}{3}\)…
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