Answer:
¹⁶⁸₇₉Au
Explanation:
The symbol of the atom is given as;
¹⁷²₈₁Tl
If undergoes a nuclear reaction and it ejects an alpha particle;
An alpha particle is the same as an helium atom
¹⁷²₈₁Tl → ₂⁴H + ₐᵇK
K is the hypothetical symbol of the new atom
b is the new mass number
a is the new atomic number;
Conserving mass number;
172 = 4 + b
b = 172 - 4 = 168
Conserving atomic number;
81 = 2 + a
81 - 2 = a
a = 79
The new compound is gold with a symbol of;
¹⁶⁸₇₉Au
