The physical property of zinc that indicates it will sink in water is its density.

Here's why:

* Density is defined as mass per unit volume. Zinc has a density of around 7.14 g/cm³.

* Water has a density of 1 g/cm³.

* Objects denser than water sink. Since zinc is significantly denser than water, a cubic centimeter of zinc will sink.

Let me know if you'd like to know more about density!