Where, e = charge
m = mass
For the given options:
Option 1.
Charge on this atom = 1e
Mass on this atom = 2m
The ratio becomes:
Option 3.
Charge on this atom = 1e
Mass on this atom = 4m
The ratio becomes:
Option 2
Charge on this atom = 1e
Mass on this atom = 1m
The ratio becomes:
Option 4.
Charge on this atom = 2e
Mass on this atom = 4m
The ratio becomes:
As, the mass of hydrogen ion is the least in the given options, so its specific charge (e/m ratio) will be the maximum.
Hence, the correct option is option 2.