Environmental Engineering in CE
Cleaning is done by(i) Scraping and removal in filters slow sand(ii) Back washing in slow sand filters(iii) Scraping and removal in filters rapid sand(iv) Back washing in rapid sand filtersThe correct answer is

(ii) and (iv)
(i) and (ii)
(i) and (iv)
(ii) and (iii)

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Environmental Engineering in CE
Sooty and sulphurous smog formed due to combustion of fossil fuels particularly in winter, continues throughout the day and night. When the moist atmospheric air's water vapor condenses on the solid particles of smoke thereby forming smog (smoke + fog), it causes

All of these
Respiratory trouble
Irritation in eyes
Poor visibility due to sky darkening

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