Question

Consider the nuclear equation below.

Answer 1

Answer;

C) 228/90Th

Explanation;

-The above nuclear equation shows a beta radiation. The nuclide X undergoes beta radiation to form 228/89 Ac.

- When an unstable nuclide undergoes beta radiation the mass number remains the same while the atomic number is increased by one.

-Therefore, we can get the mass number and the atomic number of nuclide X, The mass number would be the same as 228 (its not affected by beta radiation) and the atomic number would be 89 (88+1).

Answer 2

D. 

If it helps, try thinking of it like a simple math equation
Ac + the beta particle = X
so 228+0 and 89+-1 will give you the 228 over 88 which is Ra