Give reasons for the following statements.
1. A cork floats on water surface but an iron nail sinks in it
2. Ice floats on water.
3. A block of aluminium sinks in turpentine but floats in mercury.
4. 1 cm' block of wood weighs lesser than 1 cm block of iron
5. The solids have the highest density
please dont give sily answers it is very important
Answers
First of all: The mass per unit volume of a substance is called density (density = mass/volume). As the volume of a substance increases, its density decreases.
1. A cork floats on the surface of water but sn iron nail sinks in it because the density of the cork is much less than that of water whereas the density of an iron nail is much more than water.
The upthrust of water on the cork is greater than the weight of the cork. Hence it floats. On the other hand, the density of iron nail is more than water, and the upthrust of water on iron nail is less than that of the weight of the iron nail. Thus it sinks.
2. Liquids have a lower density than that of solids. Water is also a liquid so it should also have less density than that of solid that is ice.
Though ice is solid, it has a cage-like structure hence there are a large number of empty spaces between its particles. These spaces are larger as compared to the spaces present between the particles of water. Thus for a given mass of water, the volume of ice is greater than that of water. Hence, the density of ice is less than that of water. A substance with lower density than water can float on water. Therefore, ice floats on water.
3. It is because aluminium has lower density than mercury but higher density than turpentine.
Thats all I know about this. Sorry. But you can surely consult your teacher or a professional mentor for this answer.
4. Because centimetres cubed is a unit of volume, not weight. The two might take up the same amount of space, but iron is much more dense and as such weighs more.
5.Often solids have a higher density than liquids because the atoms or molecules are packed more closely in an ordered fashion in the solid. More order equals lower energy as it has less entropy. It is really a matter of the structure of the solid and some solids have a very elaborate crystal structure while others have a less predictable structure. Some metal alloys are non homogeneous solids.
Water is a good exception however, as the packing structure of the water molecules decreases the density, hence ice floats on water. Ice is still however in a lower state of entropy than liquid water.
Answer:
are you reading in ICSE school