becuase they do
Less than what? - It really depends on the situation. If you convert, say, a kilogram of some solid into a liquid, you'll still have a kilogram. Well, that's a unit of mass, but the weight would also be the same (9.8 newtons, assuming normal Earth gravity). On the other hand, a liter of liquid will usually weigh less than a liter of a solid of the same material.
-- a liter of baby powder and a liter of concrete -- a quart of air and a quart of mercury
It depends on the store really. Some stores' prices are different than others.
No. Water- a liquid- is not flammable. Which is very lucky thing for all of us.
True, if you allow that some prices are negative. If I pay you enough, you would buy my house on Love Canal.
cuz, some of the them have remixes or better quality then the other,
A gallon is larger than a liter, but if you measure some liquid, the number of liters will be larger than the number of gallons.
Depending on brand name or off brand, it can get as cheap as 69 cents at times. Also depends upon your particular region - in some places in the country, prices greatly differ for the same item in a similar store.
Some of them are 50 000, some of them are 125 000, some of them cost the same, and some of them don't.
in some places petrol prices have gone up but in some places they have kept the same
The units are the same, whether it is for a solid or for a liquid. Since density is defined as mass divided by volume, usually some units of mass divided by volume is used. For example, the SI unit would be kilograms / cubic meter, though it is fairly common to use kilograms / liter instead, or the equivalent grams / cubic centimeter.
They don't. Some liquids expand when they become solid and others shrink, while some do maintain the same volume.