Because the more atoms there are, the more mass there is.
mass
Because the mass depends on the size of an object.
An extensive property is a property that depends on the size or extent of a system. Examples include mass, volume, and energy.
Some properties are mass, weight, and volume.
Some properties are mass, weight, and volume.
An intensive physical property does not depend on the size of the sample. An example of an intensive physical property is density. An extensive physical property does depend on the size of the sample, such as mass and volume.
The property that depends on the size of the sample is extensive. Extensive properties, such as mass and energy, scale with the size of the sample. This means that as the sample size increases, the value of the property also increases proportionally.
It's physical! If you change the size, it's still an apple!
Mass is an example of an extrinsic property, because an extrinsic property is one that varies with and depends on the size and amount of the sample. Obviously, the more of the sample you have, the greater will be the mass. Thus, mass is an extrinsic property. Compare this to density. It doesn't matter how much of the sample you have, the density will be the same. Density is an intrinsic property.
Size is the defining factor of volume, and the greater the volume for a given density, the greater the mass. Density can be changed by changing the volume but will always depend on the chemical makeup of the substance.
Extensive (dependent on the size) and intensive (independent on the size) are terms used generally for physical properties.
there are size, texture, color, mass, hardness, and shape :D