Questions

Stratification as actually the settling down of sediments with different properties to form layers/strata over years. Stratification especially occurs on the bed of water bodies such as oceans.

Stratified sedimentary rocks are used to study the ecological conditions over previous years/eras.  

The other choices like Windstorms, Glacial Ice and Stream water are mediums which sediments are transported.

During convection, cool and dense air falls through the warmer and less dense air. The warm air having less mass is being displaced by the cooler which is much heavy. Convection always involves the air rising through the atmosphere.

i. The 'Swachh Survekshan 2017' survey results were recently announced by Urban Development Minister M Venkaiah Naidu. The total 434 cities of India were surveyed. Indore in Madhya Pradesh is India’s cleanest city while Gonda in Uttar Pradesh is the dirtiest.

ii. Gujarat has the maximum of 12 cities among the top 50 clean cities, closely followed by Madhya Pradesh with 11 and Andhra Pradesh with eight. Uttar Pradesh accounted for half of the bottom 50 cities in the cleanliness ranking.

Top 10 clean cities of India in 2017 are:

Indore (MP)
Bhopal (MP)
Visakhapatnam (Andhra Pradesh)
Surat (Gujarat)
Mysuru (Karnataka)
Tiruchirapally (Tamil Nadu)
New Delhi Municipal Council (New Delhi)
Navi Mumbai (Mumbai)
Tirupati (Andhra Pradesh)
Vadodara (Gujarat).

Top 5 Dirtiest cities of India (with Rank) in 2017 are:

Gonda (UP)- 434,
Bhusawal (Maharashtra)- 433,
Bagaha (Bihar)- 432,
Hardoi (Uttarakhand)- 431,
Katihar (Bihar)- 430.

Goitre

Gujarat