Salt is applied on the inner surface of pickle jars and the pickle is covered with oil.Why is this done?

Why is the surface tension of paints and lubricating oils kept low?

Why is the surface tension of paints and lubricating oils kept low ?

A verticle U-tube of uniform inner cross section contains mercury in both sides of its arms. A glycerine (density =1.3g//cm^3) column of length 10 cm is introduced into one of its arms. Oil of density 0.8 gm//cm^3 is poured into the other arm until the upper surfaces of the oil and glycerine are at the same horizontal level. Find the length of the oil column, density of mercury =13.6 g//cm^3

In a hydraulic lift, the input piston has surface area 20 cm^2 . The output piston has surface area of 1000 cm^2 . if a force of 50N is applied to the input piston, it raises the output piston by 2m. Calculate weight of support on output piston and its work done.

Use your brain power Sometimes, you may notice a black powder or white discs floating on the pickle or murabba, when a jar is opened after a long time. What exactly is this? Why are such food items not good to eat?

In real life, objects never travel with uniform velocity even on a horizontal surface, unless something is done? Why is it so? What is to be done?

A vertical U-tube of uniform inner cross section contains mercury in both sides of its arms. A glycerin (density =1.3 g//cm ^(3)) column of length 10 cm is introduced into one of its arms. Oil of density 0.8 gm //cm^(3) is poured into the other arm until the upper surfaces of the oil and glycerin are in the same horizontal level. Find the length of the same horizontal level. Find the length of the oil column, Density of mercury =13.6 g//cm^(3)

In a hydraulic lift , the input piston has surface area 20cm^2 . The out put piston has surface area of 1000 cm^2 . If a force of 50 N is applied to the input piston , it raise the output piston by 2 m. Calculate weight of support on out put piston and its work done.

Sometimes, you may notice a black powder or white discsfloating on the pickle or murabba, when a jar is opened after a long time. What exactly is this? Why are such food items not good to eat?

Metals get attacked by substances around it such as moisture, acids, etc. Metal is said to 'corrode' due to this attack and the process is called corrosion. Many metals like iron, copper, silver, etc. get corroded. When iron is exposed to moist air, it undergoes corrosion and a reddish brown coloured solid layer is formed on its surface. Corrosion of iron, which is known as rusting, is a serious problem as enormous amount of money is spent every year to replace damaged iron. Similarly, copper reacts with moisture and. CO_(2) in air to form a green coloured coating of basic copper carbonate on its surface. Silver acquires a black colour when exposed to air containing H_(2)S due to the formation of silver sulphide on its surface. Based on the above paragraph, answer the following question. Why do we apply paint on iron articles?