Geographical Techniques Questions and Answers

Answer: D

The keyed answer is Life would not have been possible on the earth.

Rotation on its axis gives the earth its cycle of day and night. If the earth did not rotate, the half facing the sun would have continuous day and keep heating up, while the other half would stay in darkness and become extremely cold. Such extremes of temperature would not allow life as we know it.

The other options misread the result. There would be no alternation of shorter or longer days and nights at all, so the first two options fail. Seasons are caused by the earth's revolution around the sun and the tilt of its axis, not by rotation, so 'rapid change in seasons' is also wrong.

Answer: B

The local times are 8:40 a.m. and 9:35 a.m.

IST is the local time of the standard meridian, 82°30′ E. Local time changes by 4 minutes for every degree of longitude: it is earlier to the west and later to the east.

Bengaluru lies west of the standard meridian:

\[ \begin{aligned} & 82^{\circ}30' - 77^{\circ}30' = 5^{\circ} \\ & 5 \times 4 = 20 \text{ min behind IST} \\ & 9{:}00 - 0{:}20 = 8{:}40 \text{ a.m.} \end{aligned} \]

Agartala lies east of it:

\[ \begin{aligned} & 91^{\circ}15' - 82^{\circ}30' = 8^{\circ}45' \\ & 8.75 \times 4 = 35 \text{ min ahead of IST} \\ & 9{:}00 + 0{:}35 = 9{:}35 \text{ a.m.} \end{aligned} \]

The first option gives the same two times in reverse order, which is what you get by adding for a place to the west. The 20- and 25-minute options come from miscounting the 8°45′ difference or mixing up which city is east.

Answer: C

The concepts that can be mapped are A, B and D, so the answer is A, B and D.

A map shows things that have a location and extent on the earth's surface. Ocean basins are physical features, the Strait of Gibraltar is a narrow channel between Spain and Morocco, and rainfall in July can be shown as a distribution, with isohyets or shading, on a thematic map.

Delhi's atmosphere is not a spatial feature that a map can depict; it is the state of the air above the city, described by temperature, pressure, pollution and so on, and it changes from hour to hour. So every option containing C is wrong.

Answer: B

This ability is the mapping skill.

The NCERT EVS syllabus and textbooks develop mapping skills from Class III onwards: understanding where places are relative to each other, estimating distances and using directions, first through drawing simple maps of the classroom, school and neighbourhood and later reading maps with directions and symbols.

Directional skill and positional skill each name only one part of this ability, and graphic skill refers to drawing and reading graphs and diagrams in general.

Answer: A

Both A and B are true.

The sun is at its highest point in the sky at mid-day, when it crosses the meridian of that place. A watch set to read 12 o'clock at that moment shows the time based on the sun's position at that place, and this is exactly what local time means.

Places on different meridians reach mid-day at different moments, which is why local time changes by four minutes for every degree of longitude and why countries adopt a standard time instead. Since both statements are correct, the options calling either of them false are wrong.

Answer: A

Each one-hour time zone covers 15° of longitude.

The earth turns through 360° in 24 hours, so in one hour it turns through:

\[ \frac{360^\circ}{24\ \text{h}} = 15^\circ \text{ per hour} \]

That is why the world is divided into 24 standard time zones of 15° each, and why each degree of longitude is worth 4 minutes of time. 30° would be two hours, 45° three hours and 60° four hours.

Answer: A

At 90° East it will be 6 PM.

Each degree of longitude is worth 4 minutes of time, and places east of Greenwich are ahead of it.

\[ \begin{aligned} 90 \times 4\ \text{min} &= 360\ \text{min} \\ &= 6\ \text{h ahead} \\ 12.00\ \text{noon} + 6\ \text{h} &= 6\ \text{PM} \end{aligned} \]

6 AM is what you get by going back 6 hours, which is the time at 90° West. 7 PM and 9 PM correspond to 105° E and 135° E.

Answer: B

Latitudes and longitudes help to locate places on earth.

Latitudes (parallels) run east-west and measure distance north or south of the Equator; longitudes (meridians) run north-south and measure distance east or west of the Prime Meridian. Together they form a grid, so the position of any place can be given exactly as a pair of coordinates, such as 28° N, 77° E for Delhi.

The lines are imaginary, not decorations, designs or furrows on the Earth, so the other options are wrong.

Answer: D

The true representative model of the Earth is the globe.

A globe is a three-dimensional scale model that shows the Earth's shape, and the true sizes, shapes, directions and relative positions of continents and oceans without distortion.

A map is a flat drawing of the curved surface, so it always distorts shape or area, and a satellite image is a photograph of part of the surface, not a model. A rugby ball has the wrong shape altogether.

Answer: C

Both (A) and (R) are true and (R) is the correct explanation of (A).

The earth turns 15° of longitude every hour, so places east of Greenwich are ahead of Greenwich time by 4 minutes for each degree. India's Standard Meridian is 82°30′E:

\[ \begin{aligned} 82.5 \times 4\ \text{min} &= 330\ \text{min} \\ &= 5\ \text{h}\ 30\ \text{min} \end{aligned} \]

So when it is 2:00 p.m. in London, it is 7:30 p.m. in India, and A is true. It is true precisely because India lies at 82°30′E, east of Greenwich, so R explains A.