Expansion during heating
A. Occurs only in solids
B. Decreases the density of the material
C. Occurs at the same rate for all liquids and gases
D. Increases the weight if the material

Hint:Expansion, also referred as thermal expansion, is the change in the length, width, height, or volume of any material with the change in temperature. Thermal expansion can be easily seen in solids because the atoms in solids are densely packed. Thermal expansion of solids have many applications in day-to-day life.

Complete answer:
It is a well-known phenomenon that solids expand on heating and contract on cooling. When we heat a body, it changes its dimensions depending on the shape of the body.
Now, there are three types of expansions that occurs in solids which are discussed below:
-When the expansion occurs in length, it is called linear expansion.
-When we heat a solid that will be in the form of a square, then expansion will occur on two fronts, length and breadth, this expansion is known as area expansion.
-When we heat a solid that will be in the form of a cube, then the expansion will occur on all sides that will increase the volume of the cube, this expansion is known as volume expansion.
Now, if we take an example of volumetric expansion, then we can say that on heating a substance the volume of the substance will increase but the mass will be constant. This results in a decrease in the density of the substance.

Hence, option B is the correct option.

Note:Now you might wonder why we have considered volumetric expansion and not the linear o areal expansion. This is because, most of the things that we use in real life are three dimensional. Therefore, those substances will get three-dimensional expansions that are volumetric expansion.