Longitude, Meridians, and Local Time

The governing concept is Earth's rotation and the effect of longitude on local solar time. Earth rotates from west to east, so eastern longitudes turn toward the Sun earlier than western longitudes. Consequently, sunrise, noon, and other solar events occur earlier in eastern India. Since local time changes with longitude—approximately four minutes per degree—the eastern part has a later clock reading in terms of the day's progression than the western part. Option D gives the correct cause. Altitude, rainfall, and distance from the sea can influence temperature or climate, but they do not determine the basic east–west difference in local time.

The governing concept is that local time is controlled primarily by longitude, not by the total north–south length of a country. Earth rotates 15 degrees of longitude in about one hour, or approximately four minutes per degree. Thus even a comparatively smaller east–west width can create a measurable time difference between eastern and western places. India uses a single standard time to avoid the confusion that separate local times would cause in administration, transport, communication, and daily schedules. Option A is correct. Latitude does not stop time, a coastline does not fix national time, and mountains cannot remove time differences; these options confuse unrelated geographical factors with longitude.

The governing concept is Earth’s rotation from west to east and its effect on local solar time. As Earth rotates, eastern places face the Sun earlier than western places. Consequently, the local solar time in eastern India is ahead of that in western India. Longitude provides the numerical measure of this difference: Earth rotates about 360 degrees in 24 hours, so one degree corresponds to roughly four minutes. For instance, a place 10 degrees farther east may have local solar time about 40 minutes ahead. Option A is correct. Option B reverses the direction of the relationship, while C and D incorrectly deny the established connection between longitude and time. Official clock time may be uniform, but local solar time varies by longitude.

Local time is governed primarily by longitude and Earth’s rotation. Earth rotates from west to east, so places located farther east face the Sun earlier. Consequently, sunrise, apparent noon and other solar-time events occur earlier in eastern India than in western India, making eastern local time ahead. The roughly 30° difference in longitude across India can create nearly two hours of local-time difference, using the rule of about four minutes per degree. Option A states this physical cause correctly. Latitude influences factors such as the altitude of the Sun, seasons and the length of daylight, but it does not explain the east-west local-time difference, so B is wrong. Option C describes the reference meridian for a common national time, not the cause of local time. Proximity to the sea does not make the Sun rise earlier, so D is also incorrect.

Option A is correct because the east-west direction corresponds mainly to changes in longitude, and local time is determined by longitude. The Earth rotates 360 degrees in about 24 hours, so a difference of 15 degrees of longitude represents approximately one hour of local-time difference. India’s wide east-west span therefore means that sunrise, noon, and sunset occur earlier in the east than in the west, even though the country follows one standard time. Latitude is more directly associated with north-south position and climatic variation. Coastline and total area do not provide the basis for calculating time differences.

The governing concept is the relationship between longitude and local solar time. Earth rotates 360 degrees in about 24 hours, so the time difference is approximately 4 minutes for each degree of longitude. Because India extends substantially from west to east, local solar time is not identical at all places: eastern locations experience sunrise and noon earlier than western locations. India adopts a standard meridian for a common official time, but that does not remove the underlying local-time difference. Option A correctly states the cause and effect. A coastline does not determine the standard meridian, area does not alter latitude, and a land boundary cannot create a natural parallel such as the Tropic of Cancer.

Coordinates are a fundamental map-reading tool. Latitude indicates a place’s angular distance north or south of the Equator, while longitude indicates its angular distance east or west of the Prime Meridian. Reading the northern and southern latitudes and the eastern and western longitudes of India allows a learner to locate the country, identify its directional position, and understand how far it extends. This is why option A is correct. Colouring, erasing boundaries, and estimating population are not coordinate skills. A coordinate-based answer must use positional evidence rather than merely visual features or unrelated statistical information.