Standard Time and the International Date Line MCQ Quiz - Objective Question with Answer for Standard Time and the International Date Line - Download Free PDF

The correct answer is water body only.

The International Date Line (IDL) - 

• The International Date line is an imaginary line that passes through the Pacific Ocean.
• Along with the IDL, the date changes by exactly one day when it is crossed.
• A traveller crossing the International Date Line from West to East gains a day while crossing the International Date Line from East to West loses a day.

Why is there gain or loss of the day?

• 180^o E is GMT +12hrs and 180^o W is GMT -12hrs, hence the difference between 180^o E and 180^o W is 24hrs.
• The time difference on either side of the IDL is 24hours, so the date changes as soon as one crosses IDL.

Why does it pass through the water body only?

• If the IDL passes through the land, then two regions of the same Island country or Island group would fall under different date zones.
• Thus, to avoid any confusion of date, IDL is drawn from the water body only and it is in Zig-zag manner.

The correct answer is 15 degrees.

Key Points

• Each time zone covers 15 degrees of longitude.
• There are 24 time zones in the world, so the Earth is divided into 360/24 = 15 degrees of longitude per time zone.
  • 24 degrees is the total number of degrees in a circle.
  • 20 degrees is not a common number of degrees for a time zone,.
  • 10 degrees is to Indian Standard Time o small to be a useful division of the Earth.

Important Points

• India uses a single time zone, Indian Standard Time (IST), which is UTC+5:30.
• This means that IST is 5 and a half hours ahead of Coordinated Universal Time (UTC).

The correct answer is the International dateline.

• The international date line name is given to 180° longitude due to the spherical shape of the earth.

Key Points

• Longitude:
  • Longitude is the angular distance of a point on the earth's surface along the equator, east or west from the Prime Meridian.
  • Prime Meridian is the semi-circle from pole to pole, from which all the other meridians radiate Eastwards and Westwards up to 180°.
  • 180° meridian which is also known as the International Date Line is exactly opposite the Prime Meridian.
• International Date Line:
  • The International Date Line (IDL) is an imaginary line on the surface of the Earth, that runs from the north to the south pole and demarcates one calendar day from the next.
  • It passes through the middle of the Pacific Ocean, roughly following the 180° longitude, and deviates at Aleutian Islands, Fiji, Samoa, and the Gilbert Islands.

Additional Information

• 0-degree latitude is called the equator.
• \(23.5^0S\) is called the Tropic of Capricorn.
• \(23.5^0N\) is called the Tropic of Cancer.
• \(66.5^0N\) is called the Arctic Circle.
• \(66.5^0S\) is called the  Antarctic Circle.

The correct answer is 21 March and 23 September.

Key Points

• The equinoxes occur twice a year, when the tilt of the Earth's axis is inclined neither away from nor towards the Sun, resulting in a nearly equal duration of day and night.
• The vernal (spring) equinox typically occurs on March 21, marking the start of spring in the Northern Hemisphere.
• The autumnal (fall) equinox typically occurs on September 23, marking the start of autumn in the Northern Hemisphere.
• During an equinox, the Sun crosses the celestial equator, an imaginary line projected into space above the Earth's equator.
• Both equinoxes are significant astronomical events used to define the changing of the seasons.

Additional Information

• Celestial Equator: An imaginary line that is the projection of the Earth's equator into the celestial sphere, dividing it into the northern and southern celestial hemispheres.
• Solstices: The points in the year when the Sun is at its greatest distance from the celestial equator, occurring around June 21 (summer solstice) and December 21 (winter solstice).
• Equilux: A day when the duration of light and dark is exactly equal; it occurs a few days before or after the equinox due to atmospheric refraction.
• Earth's Tilt: The 23.5-degree tilt of the Earth's rotational axis relative to its orbital plane around the Sun, responsible for the changing seasons.
• Day and Night Cycle: The rotation of Earth on its axis, which leads to the alternation of day and night. During equinoxes, this cycle results in nearly 12 hours of daylight and 12 hours of night.

The correct option is 3) Bering Strait

Important Points

• The International Date Line, often known as the Date Line, is a hypothetical line that separates each calendar day arbitrarily into two parts by extending between the North and South Poles.
• The International Date Line roughly crosses the 180° line of longitude.
  • although it diverges through the Bering Strait to the east to avoid separating Siberia,
  • and then it diverges to the west to incorporate the Aleutian Islands with Alaska.
  • Another eastward displacement south of the equator enables certain island groupings to share the same day as New Zealand.

Additional Information

• The International Date Line is a result of timekeeping systems being used all over the world that are set up so that local noon roughly coincides to the moment the sun crosses the respective local meridian of longitude.
• The International Date Line offers a consistent way to do the necessary readjustment: individuals heading eastward across the line move their calendars back one day, and those moving westward set their calendars one day ahead.

The correct answer is France.

Key Points

• A time zone is a region of the globe that observes a uniform standard time for legal, commercial, and social purposes.
• Time zones tend to follow the boundaries of countries and their subdivisions because it is convenient for areas in close commercial or other communication to keep the same time.
• France, including its overseas territories, has a total of 13 time zones. This is due to the fact that France has several territories scattered across the world, including some in the Pacific and Indian Oceans, which have different time zones.
• Russia has 11 Time Zones.
• South Africa has 2 time zones.
• India has only one-time zone. The country has officially observed India Standard Time (IST) since 1947.

The correct answer is the International Date Line.

Key Points

• The International Date Line (IDL) is an imaginary line on Earth's surface defining the boundary between one day and the next.

• The 180° meridian was selected as the International Date Line because it mostly runs through the sparsely populated Central Pacific Ocean.

• It was decided at the International Meridian Conference in 1884 in Washington, D.C. where 26 countries attended.

Important Points

• The International Date Line is located halfway around the world from the Prime Meridian (0° Longitude) or about 180° east (or west) of Greenwich, London, UK, the reference point of time zones.
• It is also known as the line of demarcation.
• The Date Line runs from the North Pole to the South Pole and marks the divide between the Western and Eastern Hemisphere.
• It is not straight but zigzags to avoid political and country borders.
• When you cross the International Date Line from west to east, you subtract a day, and if you cross the line from east to west, you add a day.
• The Date Line is not defined by international law.
• Countries are free to choose the date and time zone that they want to observe.​

Mistake Points

• Don't get confused between prime meridian (0o) and international date line (180o) they are different from each other. 

The correct answer is the International dateline.

• The international date line name is given to 180° longitude due to the spherical shape of the earth.

Key Points

• Longitude:
  • Longitude is the angular distance of a point on the earth's surface along the equator, east or west from the Prime Meridian.
  • Prime Meridian is the semi-circle from pole to pole, from which all the other meridians radiate Eastwards and Westwards up to 180°.
  • 180° meridian which is also known as the International Date Line is exactly opposite the Prime Meridian.
• International Date Line:
  • The International Date Line (IDL) is an imaginary line on the surface of the Earth, that runs from the north to the south pole and demarcates one calendar day from the next.
  • It passes through the middle of the Pacific Ocean, roughly following the 180° longitude, and deviates at Aleutian Islands, Fiji, Samoa, and the Gilbert Islands.

Additional Information

• 0-degree latitude is called the equator.
• \(23.5^0S\) is called the Tropic of Capricorn.
• \(23.5^0N\) is called the Tropic of Cancer.
• \(66.5^0N\) is called the Arctic Circle.
• \(66.5^0S\) is called the  Antarctic Circle.

The correct answer is water body only.

The International Date Line (IDL) - 

• The International Date line is an imaginary line that passes through the Pacific Ocean.
• Along with the IDL, the date changes by exactly one day when it is crossed.
• A traveller crossing the International Date Line from West to East gains a day while crossing the International Date Line from East to West loses a day.

Why is there gain or loss of the day?

• 180^o E is GMT +12hrs and 180^o W is GMT -12hrs, hence the difference between 180^o E and 180^o W is 24hrs.
• The time difference on either side of the IDL is 24hours, so the date changes as soon as one crosses IDL.

Why does it pass through the water body only?

• If the IDL passes through the land, then two regions of the same Island country or Island group would fall under different date zones.
• Thus, to avoid any confusion of date, IDL is drawn from the water body only and it is in Zig-zag manner.

The correct answer is 15 degrees.

Key Points

• Each time zone covers 15 degrees of longitude.
• There are 24 time zones in the world, so the Earth is divided into 360/24 = 15 degrees of longitude per time zone.
  • 24 degrees is the total number of degrees in a circle.
  • 20 degrees is not a common number of degrees for a time zone,.
  • 10 degrees is to Indian Standard Time o small to be a useful division of the Earth.

Important Points

• India uses a single time zone, Indian Standard Time (IST), which is UTC+5:30.
• This means that IST is 5 and a half hours ahead of Coordinated Universal Time (UTC).

The correct answer is Horizontal equal halves.

Key Points

• The equator is an imaginary line that divides the earth into two equal parts, i.e. in the Northern Hemisphere and the Southern Hemisphere.
• Tropic of Cancer is the northerly circle of latitude on earth at which the sun gets directly overhead.
• Tropic of Capricorn is the southernmost latitude where the sun is directly overhead.

The correct answer is Allahabad.

Key Points

• Uttar Pradesh
  • Indian Standard Time is calculated on the basis of 82.5°E longitude in the city of Mirzapur, Uttar Pradesh, which is situated approximately on the corresponding longitude reference line.​
  • IST is based on longitude 82.5°, which passes through Mirzapur, near Allahabad in Uttar Pradesh.
• Hence option 2 is correct.

Additional Information

• Indian Standard Time
  • IST is based on longitude 82.5°, which passes through Mirzapur, near Allahabad in Uttar Pradesh.
  • It is 5 hours 30 minutes ahead of Greenwich Mean Time (GMT), now called the Universal Coordinated Time (UTC).
  • The keeper of the time in India is the CSIR-National Physical Laboratory (NPL), New Delhi, which records time using five caesium atomic clocks.

The correct answer is 82° 30’ E longitude.

Mistake Points

• The standard meridian of India is 82°30'E and it passes through Mirzapur in Uttar Pradesh.
• 82.5 means 82° and 30', one degree is presented by 60 minutes and 30 minutes means the half or .5 of one degree. So, 82.5° E and 82°30'E are the same.

Key Points

The Standard - Meridian of India:

• Standard Meridian is the longitude that is used to describe the time of a country.
• ​Ideally should be the same for the whole country and all the places in a country should follow this same time. 
• The Standard Meridian of India is located at 82°30'E.
• The time along this latitude is taken as the official time across the country.
• The standard meridian of India is 82°30'E and it passes through Mirzapur in Uttar Pradesh.

Hence, the standard meridian of India is located at 82° 30’ E longitude which determines the time for the whole country.

Important Points

• India is located entirely in the Northern Hemisphere, with the mainland extending between 8°4'N and 37°6'N latitudes and 68°7'E and 97°25'E longitudes.

The correct answer is moves forward by one day.

• When a ship crosses the International Date Line from west to east, its time moves forward by one day.

Key Points

International Date Line (IDL):

• The International Date Line (IDL) is an imaginary line on the surface of the Earth, that runs from the north to the south pole and demarcates one calendar day from the next.
• It passes through the middle of the Pacific Ocean, roughly following the 180° longitude but it deviates at Aleutian Islands, Fiji, Samoa, and the Gilbert Islands.
• The International Dateline is on the opposite side of the Earth-Prime Meridian.
• A traveller crossing the International Date Line eastbound (i.e., from Japan to the USA) subtracts one day, or 24 hours so that the calendar date to the west of the line is repeated after the following midnight.
• Crossing the IDL westbound i.e from west to east results in 24 hours being added, advancing the calendar date by one day.

Important Points

• While the world is divided into 24 time zones, there has to be a place where there is a difference in days, somewhere the day truly “starts” on the planet. The 180° line of longitude is approximately where the International Date Line passes.
• The time at this longitude is exactly 12 hours from the 0° longitude, irrespective of one travels westward or eastward from the Prime Meridian. We know that time increases east of the Prime Meridian and decreases to its west. Hence, for a person moving east of the Prime Meridian, the time would be 12 hours less than the time at 0° longitude.
• For another person moving westward, the time would be 12 hours more than the Prime Meridian.
• For example, a person moving eastward on Tuesday will count the day as Wednesday once the International Date Line is crossed. Similarly, another person starting his journey on Wednesday, and moving westward will count the day as Tuesday after crossing the line.

Confusion Points

•  While moving eastward i.e. from west to east the calender advances by one day but the day is lost.

The correct answer is Rajasthan.

Key Points

• The Tropic of Cancer in India passes through eight states in India.
• These states are:
  • Gujarat,
  • Rajasthan,
  • Madhya Pradesh,
  • Chhattisgarh,
  • Jharkhand,
  • West Bengal,
  • Tripura, and
  • Mizoram
• The shortest length of the Tropic of Cancer in India is in Rajasthan.

 Thus, we can say that the shortest length of the Tropic of Cancer in India is in Rajasthan.