Fifteen grams of a liquid plastic are frozen in a physical change that increases the volume. what can be known about the plastic after the change ?

The parameter that is affected with the physical change that is brought about by the increasing of the volume of the substance is density. In physical science, a density of the object is equal to the quotient when the mass is divided by the volume. This can be expressed as below.
    D = m/v
where D is density, m is the mass, and v is the volume.

When the mass is constant, and by the given it is said that the volume is increased then, the density decreases. This is because by the equation for density it can be concluded that the volume is inversely proportional to the density. 

Definitely the indoraptor