Interesting facts about Timezones

• China is the largest country with just a single time zone . China follows a single time zone of UTC+08:00 , even though China spans almost five geographical time zones. In the past China did have 5 time zones, but a single time zone was adopted in 1940s. 
• This has some interesting consequences like:
• The border between Afghanistan and China has the largest time change for any land border. Afghanistan follows UTC+4:30, while China follows UTC+08:00. This leads to a difference of 3.5 hours on crossing the border
• References 
• China TimeZones
• India with an east-west length of 2933kms has just one time zone ( IST, UTC+5:30). There has been proposals for having 2-3 time zones. In the past there were multiple timezones
• DST seems to have been used during wars. 
• References
• Indian_Standard_Time
  
• Bombay_Time
  
• Calcutta_Time
  
• Madras_Time
  
• Port_Blair_mean_time
  

• Mongolia Smallest contiguous country with multiple time zones
• References
• What-is-the-smallest-country-to-have-2-or-more-time-zones-running-through-it
• Time_in_Mongolia
  
• Federated States of Micronesia has an area of just 702 sq kms, but has two times zones UTC+10 and +11. This is because this island country consists of small islands spread over a large area (2700kms long) , Hence even though it is only 702 sq kms in area, it has the 14th largest EEZ
• Kiribati has 3 time zones  UTC+12, +13 and +14 even though it is just 811 sq kms in area. This is because the islands are spread across a large area
• It has the most advanced time zone UTC+14
• It is the only country spread over all the 4 hemispheres
• Papua New Guinea has two time zones 
• Democratic Republic of the Congo has two time zones
• Kazakhstan has two time zones
• Indonesia has 3 time zones
• Nepal follows UTC +5:45. The only country which follows quarter hour precision. There are couple of other time zones with quarter hour precision
• UTC+08:45
• UTC+12:45
• Greenland has 4 time zones ( from wiki )
• UTC−04:00 — Thule Air Base in Greenland
• UTC−03:00 — most of Greenland, including inhabited south coast and west coast
• UTC−01:00 — Ittoqqortoormiit and surrounding area in Greenland's Tunu county
• UTC±00:00 — Danmarkshavn weather station and surrounding area in Greenland's Tunu county, Faroe Islands
• Chile has 3 time zones
• Mexico has 4 time zones
• France has the most number of time zones ( due to its colonial past ) - 12/13
• USA 11 time , but this is due to its possessions in Pacific etc
• Russia has 11 time zones, out of these 10 are contiguous Kaliningrad_Oblast which is an exclave of Russia
• Sri Lanka seems to have changed their time zone many times Sri_Lanka_Standard_Time

References

List_of_time_zones_by_country

https://www.timeanddate.com/time/map/

https://www.worldtimeserver.com/learn/unusual-time-zones/