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Atoms And Molecules
What do you understand by buoyancy and centre of buoyancy?
The upward force acting on a body immersed in a fluid is called upthrust or force of buoyancy and the phenomenon is called buoyancy.
When a body is immersed partially or wholly in a fluid, it displaces fluid. The displaced fluid tends to regain its original condition. Durig this time, it exerts an upward force on the body which is called as Buoyancy.
For example, a cork taken inside water comes to the surface after experiencing an upward thrust.
The buoyancy acts through the centre of gravity of the displaced fluid which is called centre of buoyancy.
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Calculate the number of molecules of sulphur (S8) present in 16 gm of solid sulphur.
Calculate the number of aluminium ions present in 0.56 gm of aluminium oxide.
Explain law of conservation of mass.
50 g of 10% lead nitrate is mixed with 50 g of 10% sodium chloride in a closed vessel. After the reaction has taken place, it was found that 6.83 g of lead chloride was precipitated. Besides, the reaction mixture contained 90 g water and sodium nitrate. Calculate the amount of sodium nitrate formed.
Name and explain two important laws of chemical combination ?
What are the postulates of Dalton’s atomic theory of matter?
Hydrogen and oxygen combine in two different ways to produce water and hydrogen peroxide. Which of Dalton’s law does this observation confirm? Explain.
State drawbacks of Dalton’s atomic theory of matter.
Give an illustration based on atomic theory for the difference between an element, compound and mixture.
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