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Which of the following reactions are forbidden and why? \begin{aligned} p &\longrightarrow n + e^+ + u_e \\\\ \pi^+ &\longrightarrow \mu^+ + u_\mu \\\\ \text{H}^2 &\longrightarrow \text{He}^3 + e^- + e \end{aligned}
The number of alpha particles emitted per gm of radium each second is 3.71 \times 10^{10}. Atomic weight of radium is 226. Calculate its half-life in years.
How many types of neutrinos exist? How do they differ in their masses?
Calculate the Q-value of the reaction: {}^{9}_{4}\mathrm{Be}({}^{4}_{2}\mathrm{He},\mathrm{n}){}^{12}_{6}\mathrm{C} Given: \begin{aligned} \text{Mass }({}^{9}_{4}\mathrm{Be}) &= 9.01283\,\mathrm{u}\\ \text{Mass }({}^{4}_{2}\mathrm{He}) &= 4.002603\,\mathrm{u}\\ \text{Mass }({}^{12}_{6}\mathrm{C}) &= 12.000\,\mathrm{u}\\ \text{Mass }(\mathrm{n}) &= 1.0086652\,\mathrm{u} \end{aligned}
State the quantum numbers I_z, Y and S for the uds quarks and antiquarks. Which combination of these leads to the formation of (i) proton and (ii) neutron?