WBJEE · Chemistry · Chemical Kinetics
The half-life of a radioactive element is 10 hours. How much will be left after 4 hours in \(1 \mathrm{~g}\) atom sample?
- A \(45.6 \times 10^{23}\) atoms
- B \(4.56 \times 10^{23}\) atoms
- C \(4.56 \times 10^{21}\) atoms
- D \(4.56 \times 10^{20}\) atoms
Answer & Solution
Correct Answer
(B) \(4.56 \times 10^{23}\) atoms
Step-by-step Solution
Detailed explanation
\(t_{1 / 2}=10 \mathrm{hr} . \quad \mathrm{K}=\frac{0.693}{10}\) \(4=\frac{2.303 \times 10}{0.693} \log \frac{1}{\mathrm{~N}}\) \(\log \frac{1}{\mathrm{~N}}=\frac{4 \times 0.693}{2.303 \times 10}=0.12036\) \(\log \mathrm{N}=-0.12036=\overline{1} .87964\)…
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