a) Đúng. \(_6^{14}{\rm{C}} \to _{ - 1}^0{\rm{e}} + _7^{14}\;{\rm{N}}\)

b) Sai. Hằng số phóng xạ: \(\lambda = \frac{{\ln 2}}{{\;{\rm{T}}}} = \frac{{\ln 2}}{{5730.365.24.60.60}} \approx 3,{836.10^{ - 12}}\left( {\;{{\rm{s}}^{ - 1}}} \right)\)

c) Đúng. \({N_0} = \frac{{{H_0}}}{\lambda } = \frac{{10 \cdot {{10}^{ - 3}} \cdot 3,7 \cdot {{10}^{10}}}}{{3,836 \cdot {{10}^{ - 12}}}} \approx 9,646 \cdot {10^{19}}\)

\({n_0} = \frac{{{N_0}}}{{{N_A}}} = \frac{{9,646 \cdot {{10}^{19}}}}{{6,02 \cdot {{10}^{23}}}} \approx 1,6 \cdot {10^{ - 4}}\;{\rm{mol}}\)

\({m_0} = {n_0}M = 1,6 \cdot {10^{ - 4}} \cdot 14 = 2,24 \cdot {10^{ - 3}}g = 2,24mg\)

d) Sai. \({\rm{H}} = {{\rm{H}}_0} \cdot {2^{\frac{{ - {\rm{t}}}}{{\rm{T}}}}} \Rightarrow 1 - \frac{{2,5}}{{100}} = {2^{\frac{{ - {\rm{t}}}}{{5730}}}} \Rightarrow {\rm{t}} \approx 209,3\) năm

Trong hạt nhân oxygen \(_8^{17}0\) có