1. The Sadiya-Dhubri stretch of the Brahmaputra River has been declared National Waterway 2 by the National Waterways Act 1988.

2. The waterway extends from Dhubri to Sadiya for a distance of 891 km.

1. During an earthquake, the velocity of the upper part of the waves will increase along with the increase in density which will propel the object passing through it.

2. Earthquake shock When seismic waves occur in a place with soft soil sediments, their propagation increases the natural period, which produces an echo.

Oceans make up 97.3 per cent of the total water on Earth. The ice caps have 2 per cent of total water. Groundwater accounts for 0.68 per cent of total water. Rivers account for 0.0001 per cent of the total water.