(i) What characteristic property of nuclear force explains the constancy of binding energy per nucleon `(BE//A)` in the range of mass number 'A' lying `30 lt A lt 170` ?
(ii) Show that the density of nucleus over a wide range of nuclei is constant-independent of mass number A.

Explanation

To solve the given question, we will break it down into two parts as specified.

### Part (i): Characteristic Property of Nuclear Force

1. **Understanding Nuclear Force**: The nuclear force is a strong interaction that holds protons and neutrons (nucleons) together in the nucleus. It is characterized by its short-range nature.

2. **Short-Range Nature**: The nuclear force acts effectively only at distances on the order of 1 femtometer (10^-15 meters). Beyond this range, the force diminishes rapidly and becomes negligible.

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