28.
Assertion A : Large size stones are required in stone revetment in shore protection.
Reason R : Resistance of stone to wave force is proportional to its volume and wave force is proportional to the exposed area of the stone.
Select your answer based on the coding system given below.

29.
Assertion A : Intervention of undulations in the sea bed reduces the depth of wave at the section.
Reason R : No wave can have a height greater than the depth of water through which it passes.
Select your answer based on the coding system given below:

30.
Assertion A : Marine structures are made specially bulky and strong.
Reason R : Sea insects result in undermining of the hardest and the soundest building material.
Select your answer based on the coding system given below: