Calcium oxide reacts vigorously with water to produce slaked lime whose solution is used for white-washing walls. This slaked lime reacts with component (A) in air to form a thin layer of component (B) to give a shiny finish. What are the components (A) and (B)?

The size of particles being studied in ‘nano-technology’ is about

The weight of an object is due to

The direction of acceleration in uniform circular motion is along the

How many internal reflections of light take place in the formation of primary rainbow?

Which one of the following sodium compounds is used for softening hard water?