What are the physical factors that can affect the density of a sample?

Question

If you increase the Temperature of the Sample, whether it affect the density of sample

Answer 1

If you increase the temperature of most substances they will expand, i.e their density will decrease.  How much this change is depends on what the substance is and there are instances of the density decreasing with decrease (rather than increase) of temperature (e.g. water below 5 degrees).  Most solids and liquids expand little compared to gases for the same tempertaure increase.

Pressure is another parameter which will cause density this time to rise as it is increased, again most noticeably in the case of gases.

Answer 2

The mass of the sample will always remain the same, no matter what state it is in, so the only way to change the density is to change the volume. Water is a good example. Water is most dense at 4 degrees C, because at 0, it is Ice and expands which makes it less dense.