Using general tendencies and the chart given in the introduction, predict the most likely mode of decay of each of the following radioactive isotopes.

Drag the appropriate items to their respective bins.

Note: Based on the valley of stability, the following processes generally tend to produce more stable neutron-to-proton (n/p) ratios:
Nuclei with Z≥84 tend to undergo α emission.
Nuclei with high n/p ratios undergo β ( 0−1e) emission.
Heavy nuclei with low n/p ratios are more likely to undergo electron ( 0−1e) capture.
Light nuclei with low n/p ratios are more likely to undergo positron (01e) emission.
The classification "high" or "low" n/p ratio can be determined by finding the coordinates on the graph that correspond to the number of protons (x or horizontal value) and neutrons (y or vertical value) in a given isotope. Then, observe whether this set of coordinates is above, within, or below the stability valley.

My Effort to Solve it myself:
K-47, Hg-190, Th-232, Na-20, I-137

# of.... p n order of greatest atomic mass
K: 19 28 4
Hg: 80 110 2
Th: 90 142 1
Na: 11 9 5
I: 53 84 3

Stability of a nucleus is decided by the neutron /proton (n/p) ratio. For lower elements of atomic number 1-20, n/p=1. Elements with higher atomic numbers tend to have a slight excess of neutrons to reduce the repulsive forces between the protons.

Beta emission decreases the n/p ratio, positron emission increases the n/p ratio, electron capture increases the n/p ratio and alpha decay increases the n/p ratio.

Note that a nucleus may undergo several decay processes before stable nucleus (nuclei) is/are formed.