The steps below show three of the steps in the radioactive decay chain for ²³²₉₀Th. The half-life of each isotope is shown below the symbol of the isotope. (a) Identify the type of radioactive decay for each of the steps (i), (ii), and (iii). [Sections 21.2 and 21.4]

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1. Step 1: Identify the initial isotope and its decay product for step (i). The initial isotope is ^{232}_{90}Th and the decay product is ^{228}_{88}Rn.
2. Step 2: Determine the type of decay for step (i). Since the atomic number decreases by 2 and the mass number decreases by 4, this indicates an alpha decay.
3. Step 3: Identify the initial isotope and its decay product for step (ii). The initial isotope is ^{228}_{88}Rn and the decay product is ^{228}_{89}Ac.
4. Step 4: Determine the type of decay for step (ii). Since the atomic number increases by 1 and the mass number remains the same, this indicates a beta decay.
5. Step 5: Identify the initial isotope and its decay product for step (iii). The initial isotope is ^{228}_{89}Ac and the decay product is ^{228}_{90}Th. Determine the type of decay for step (iii). Since the atomic number increases by 1 and the mass number remains the same, this indicates a beta decay.