Terbium-147 undergoes positron emission to become a stable atom. what is that stable atom?

We have to get the stable atom formed after positron emission from Terbium-147.

The stable atom is (D) ₆₄Gd¹⁴⁷.

Positron is radioactive decay. Positron is a type of beta particle β⁺.

Positron emission decreases proton number relative to neutron number, positron decay results in nuclear transmutation, changing an atom of one chemical element with an atomic number that is less by one.

Terbium on positron emission produces Gadolinium with one atomic number less than Terbium. So, the positron emission reaction is as shown below:

Tb¹⁴⁷→ ₆₄Gd¹⁴⁷ + ₁e⁰