Answer:
![t_(1)/(2)](https://img.qammunity.org/2020/formulas/chemistry/middle-school/fd6zadximnla3v6zx0fegd9b1ldd9a3bu9.png)
Explanation:-
1. Activation energy is the extra energy required by the reactants to cross the energy barrier and convert to products. It is designated by the symbol
.
2. Half life is the time taken by a reactant to reduce to its original concentration. It is designated by the symbol
.
3. Alpha decay: In this process, alpha particles is emitted when a heavier nuclei decays into lighter nuclei. The alpha particle released has a charge of +2 units.
![_Z^A\textrm{X}\rightarrow _(Z-2)^(A-4)+_2^4\alpha](https://img.qammunity.org/2020/formulas/chemistry/middle-school/tfnwh95nnutwvwvrw5xfrbsrbw3k70hbqq.png)
4. Beta-decay: In this process, a neutron gets converted into a proton and an electron releasing a beta-particle. The beta particle released carries a charge of -1 units.
![_Z^A\textrm{X}\rightarrow _(Z+1)^A\textrm{Y}+_(-1)^0\beta](https://img.qammunity.org/2020/formulas/chemistry/middle-school/xra4h83wc9g8m6mnyjkdu6zsvpk9ti7p7b.png)