The graph in Figure 16.64 is a plot of electric potential versus distance from an object. Which of the following could be the object?

(1) A neutron, (2) A sodium ion (Na+), (3) A chloride ion (Cl−), (4) A proton, (5) An electron

The electric potential at every place in an electric field is equal to the quantity of electric potential energy divided by the amount of charge at that point.

The potential of any object is related to its charge is given by,

$v=\frac{KQ}{r}$

Here, K is the coulomb constant, Q is the charge on the object and r id the distance between reference point and object.

The sign of the potential depends on the sign of the charge. In figure 16.64, the potential in the quarter, which means the potential of the object is positive and the charge of the object must be positive. Based on this, a sodium ion (Na) and a proton are the positive objects.

Thus, the correct answer for positive charge objects is (2) a sodium ion (Na) and (4) a proton.