A river is the source of water for water supply to a town. Its water is very turbid and polluted. The correct sequence of steps for treating the river water would be :
Which of the following variations of magnetic declination are correctly matched ? 1. Diurnal variation..........Variation whose time period varies from 100-350 years 2. Annual variation.........Annual rate of change of secular variation 3. Secular variaiion..........Variation of declination periodic in character 4. Irregular variation.........Caused due to magnetic storms in earth's magnetic field Select the correct answer using the codes given below :
