Final Answer:
Nuclear Equations:
a) Pb-211:
82
211
Pb
82
211
Pb
b) Tl-207:
81
207
Tl
81
207
Tl
c) Th-234:
90
234
Th
90
234
Th
d) Pa-234:
91
234
Pa
91
234
Pa
Step-by-step explanation:
A nuclear equation represents the composition of a nucleus before and after a nuclear reaction. In these cases, it seems you're simply provided with the nuclear symbols for each isotope.
For example, Pb-211 represents an isotope of lead with a mass number of 211 and an atomic number of 82. Similarly, Tl-207 represents an isotope of thallium with a mass number of 207 and an atomic number of 81.
No nuclear reactions are provided, so these are just the nuclear symbols for the specified isotopes. If there were nuclear reactions, additional information would be needed to show the process of decay, fusion, or fission.