5. A substance which contains less number of
molecules per unit volume is said to be denser.
Answers
Answer:
Density is the mass of an object divided by its volume. Density often has units of grams per cubic centimeter (g/cm3). Remember, grams is a mass and cubic centimeters is a volume (the same volume as 1 milliliter).
Answer:
Density of a substance is usually defined and as the mass per unit volume of the substance. In simpler language, how many grams or kilograms or pounds will be the mass of that substance if we take a fixed volume of the substance, say a 1cm cube or 1 litre of it or 1m cube.
The easiest and most common example to demonstrate the concept is that of water. If we take 1 cm cube of water at 4 degree Celcius, it will have a mass of 1 gram. So, density of water is 1gm/cm^3 (per cm cube). With a little larger unit, 1 cube of water measuring 10cm X 10cm X 10cm (which is the definition of 1 litre) will have a mass of 1 kg exactly, at 4 degree C. Thus, density of water may also be expressed as 1kg/cm.
Often, density is not expressed in absolute terms i.e. as above but in terms of specific gravity/density. It is nothing but a comparison of the density of that substance with that of water. Lets say we have a substance S. The mass of 1 cm cube of S has a mass of 2gm. We can express this information as 2gm/cm^3 or simply say that substance S has a specific gravity of 2.
There are some interesting information abt density of substances. The least will obvious will be that of gasses (for which we need to specify not only temperature but also pressure). Osmimum has the highest density among elements, abt 22gm/cm^3, if i remember correctly. For comparison, gold has around 19 and mercury around 13.
Neutron stars may have a density of several tons per cm cube .
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