Looking for the most authentic, 100% textbook-grounded DAV Class 6 Social Science Chapter 3 Solutions: Locating Places on the Earth? Based strictly on the prescribed DAV CMC textbook We and Our World, this master guide provides comprehensive solutions for Section A (Tick the correct option with reasons), Section B (Fill in the blanks), Section C (Match the following), Section D (Short Answer Questions), Section E (Detailed Long Answer Questions), Value-Based Questions (VBQ), HOTS, numerical longitude-time calculations, multi-column comparison tables (Latitudes vs Longitudes, Torrid vs Temperate vs Frigid Zones), and authentic DAV Board Examination Previous Years’ Questions (2018-2024) with step-by-step marking schemes.
Section A: Tick (✓) the Correct Option
1. The total number of parallels of latitude drawn at an interval of 1° on the globe is:
(a) 180
(b) 181
(c) 360
(d) 90
Answer: (b) 181
Detailed Justification: There are 90 parallels of latitude in the Northern Hemisphere, 90 parallels in the Southern Hemisphere, plus the Equator (0° latitude) as the central baseline: 90 + 90 + 1 = 181 parallels (counting the North and South Poles as points).
2. The Tropic of Cancer is situated at:
(a) 23½° S
(b) 66½° N
(c) 23½° N
(d) 0°
Answer: (c) 23½° N
Detailed Justification: The Tropic of Cancer is the parallel of latitude located at 23½° North of the Equator, marking the northernmost limit where the midday sun can be directly overhead at the June solstice.
3. The Prime Meridian passes through the Royal Astronomical Observatory located at:
(a) Paris
(b) Greenwich (near London)
(c) New York
(d) Rome
Answer: (b) Greenwich (near London)
Detailed Justification: By international agreement in 1884, the meridian passing through the Royal Observatory at Greenwich, England, was officially designated as the zero meridian (0° longitude) or Prime Meridian.
4. The time difference between two consecutive longitudes separated by 1° is:
(a) 1 hour
(b) 15 minutes
(c) 4 minutes
(d) 24 minutes
Answer: (c) 4 minutes
Detailed Justification: The Earth rotates 360° on its axis in 24 hours (1,440 minutes). Therefore, the time taken to rotate through 1° of longitude is: 1,440 minutes ÷ 360° = 4 minutes.
5. The standard meridian adopted to calculate the Indian Standard Time (IST) is:
(a) 82½° W
(b) 80° E
(c) 82½° E (82°30′ E)
(d) 75° E
Answer: (c) 82½° E (82°30′ E)
Detailed Justification: To maintain uniformity of time across India’s wide longitudinal extent (from 68°7′ E in Gujarat to 97°25′ E in Arunachal Pradesh), the central meridian passing near Mirzapur (Prayagraj, Uttar Pradesh) at 82°30′ E was chosen as India’s Standard Meridian.
Section B: Fill in the Blanks
- The imaginary line that divides the Earth into two equal halves – Northern and Southern Hemispheres – is called the Equator (0° latitude).
- The intersecting network or criss-cross mesh of parallels of latitude and meridians of longitude on a globe is called the Geographical Grid.
- The zone lying between the Arctic Circle (66½° N) and the North Pole (90° N) is the North Frigid Zone.
- Places located to the East of the Prime Meridian gain time and are ahead of Greenwich Mean Time (GMT).
- The International Date Line is situated along the 180° meridian and deviates in places to avoid cutting across island groups and sovereign nations.
Section C: Match the Following
| Column A (Important Latitude / Meridian) | Column B (Exact Angular Position) |
|---|---|
| 1. Tropic of Capricorn | 23½° S (Southern Hemisphere) |
| 2. Arctic Circle | 66½° N (Northern Hemisphere) |
| 3. Antarctic Circle | 66½° S (Southern Hemisphere) |
| 4. Prime Meridian | 0° Longitude (Greenwich) |
| 5. North Pole | 90° N Latitude |
Section D: Short Answer Questions
Question 1: What are Parallels of Latitude? Mention two of their key characteristics.
Answer: Parallels of latitude are imaginary circular horizontal lines drawn around the globe parallel to the Equator. Key characteristics are:
1. Constant Parallel Spacing: All parallels run in an East-West direction and are strictly equidistant from each other (approximately 111 km apart on the ground). They never intersect or cross one another.
2. Decreasing Circumference: The Equator (0°) is the largest circle (Great Circle). As one moves towards the poles, the circumferences of the parallels progressively decrease until they become mere points at 90° N and 90° S.
Question 2: What are Meridians of Longitude? Mention two of their key characteristics.
Answer: Meridians of longitude are imaginary semi-circular vertical lines running from the North Pole to the South Pole. Key characteristics are:
1. Equal Length & Convergence: Unlike parallels of latitude, all meridians of longitude are identical in length (semi-circles). They converge and meet at both the North Pole and South Pole.
2. Variable Distance: The distance between two meridians is maximum at the Equator (about 111.3 km) and gradually narrows down to zero at the poles.
Question 3: Distinguish clearly between Latitudes and Longitudes.
Answer: Below is a clear pedagogical comparison:
| Feature | Parallels of Latitude | Meridians of Longitude |
|---|---|---|
| Direction of Line | Drawn horizontally East to West. | Drawn vertically North to South. |
| Geometric Shape | Complete concentric full circles (except poles). | Semi-circles joining the two poles. |
| Total Count | 181 parallels (90° N + 90° S + Equator 0°). | 360 meridians (180° E + 180° W). |
| Length Variation | Lengths decrease from Equator towards poles. | All meridians are of exactly equal length. |
| Primary Geographic Function | Determine climate and heat zones. | Calculate local time and standard time. |
Question 4: What is the significance of the Geographical Grid?
Answer: The Geographical Grid is the network created by the intersection of parallels of latitude and meridians of longitude at right angles. By knowing the precise latitude and longitude coordinates of any point (for example, New Delhi is approximately 28°38′ N and 77°12′ E), its absolute, unambiguous geographic location on the globe can be determined instantly by navigators, pilots, and GPS satellites.
Question 5: Why is the International Date Line not a straight line?
Answer: The International Date Line (IDL) lies approximately along the 180° meridian. If it were drawn as a straight meridian, it would pass through landmasses and island archipelagos like Fiji, Tonga, and Siberia. This would result in two different calendar days and dates within the same small island nation, causing severe confusion in commerce, legal contracts, and daily life. Therefore, the IDL bends and zig-zags across the Bering Strait and Pacific islands to keep whole countries on the same calendar day.
Section E: Long Answer Questions
Question 1: Explain the three Heat Zones of the Earth with the help of a neat comparative table. Why do temperatures vary across these zones?
Answer: Due to the spherical shape of the Earth, solar rays strike the surface at different angles. The Earth is divided into three distinct thermal or heat zones:
| Heat Zone | Latitudinal Extent | Angle of Sun Rays | Climatic Characteristics |
|---|---|---|---|
| 1. Torrid Zone | Between Tropic of Cancer (23½° N) and Tropic of Capricorn (23½° S). | Sun is directly overhead (vertical rays) at least once a year at all points. | Receives maximum solar insolation; experiences high, hot temperatures throughout the year. |
| 2. Temperate Zone | North: 23½° N to 66½° N. South: 23½° S to 66½° S. | Sun rays are always slanting; never overhead at midday. | Moderate climate – neither scorching hot in summer nor unbearable cold in winter. |
| 3. Frigid Zone | North: 66½° N to 90° N. South: 66½° S to 90° S. | Extremely oblique, slanting rays that barely rise above the horizon. | Severe, perpetual cold; surface remains frozen under ice and snow for most of the year. |
Reason for Temperature Variation: Vertical rays in the Torrid Zone concentrate solar heat over a small surface area and penetrate through a thinner atmospheric layer. In contrast, slanting rays in the Temperate and Frigid Zones spread heat over a larger surface area and pass through a much thicker layer of atmosphere where significant heat is absorbed and scattered.
Question 2: Explain the relationship between Longitude and Time. Solve a practical numerical problem: “If it is 12:00 noon at Greenwich (0°), what will be the local time at 60° E longitude and 75° W longitude?”
Answer:
1. Basic Mathematical Principle:
• Earth completes one 360° rotation in 24 hours.
• In 1 hour, Earth rotates: 360° ÷ 24 = 15° of longitude.
• In 4 minutes, Earth rotates: 1° of longitude.
• Golden Cartographic Rule: East-Gain-Add (E.G.A.) – Places to the East see the Sun earlier and are ahead in time (+4 min/degree). West-Lose-Subtract (W.L.S.) – Places to the West see the Sun later and are behind in time (−4 min/degree).
2. Numerical Calculation (Part A: 60° E Longitude):
• Difference in longitude from Greenwich = 60° − 0° = 60°.
• Time difference = 60 × 4 minutes = 240 minutes = 4 hours.
• Since 60° E is to the East of Greenwich, time will be ahead: 12:00 noon + 4 hours = 4:00 PM.
3. Numerical Calculation (Part B: 75° W Longitude):
• Difference in longitude from Greenwich = 75° − 0° = 75°.
• Time difference = 75 × 4 minutes = 300 minutes = 5 hours.
• Since 75° W is to the West of Greenwich, time will be behind: 12:00 noon − 5 hours = 7:00 AM.
Value-Based Question (VBQ) with Ethical Evaluation
Contextual Scenario:
India has a longitudinal breadth of approximately 30° from Dwarka in Gujarat to Dibrugarh in Assam, creating a local time difference of nearly two hours. However, the Indian Government adopted a single standard time (IST) based on 82°30′ E.
Questions for Ethical Reflection:
1. Why is having a single uniform Standard Time crucial for national unity and administration?
Answer: A single standard time prevents massive operational chaos in nationwide railway schedules, airline flights, live national television broadcasts, stock market operations, and board examination timings, fostering a feeling of administrative cohesion and unity across a diverse country.
2. What civic virtue is highlighted by citizens adapting to national standardized schedules?
Answer: It reflects collective discipline, mutual accommodation, and respect for orderly institutional functioning over individual regional preferences.
Higher Order Thinking Skills (HOTS) Questions
HOTS 1: When a cricket match starts in London at 10:00 AM GMT, at what time will a student in India watch the live telecast?
Answer: India’s Standard Time is based on 82°30′ E. Time difference from GMT = 82.5 × 4 minutes = 330 minutes = 5 hours and 30 minutes ahead (+5:30). Therefore, a match starting at 10:00 AM in London will be broadcast live in India at: 10:00 AM + 5 hours 30 minutes = 3:30 PM IST.
HOTS 2: What happens to a traveller who crosses the International Date Line from East to West?
Answer: When a traveller crosses the International Date Line from East to West (for instance, travelling from the United States to Japan), they cross into the Eastern Hemisphere and gain a day (i.e., they must advance their calendar forward by one full day, turning Sunday into Monday).
Authentic DAV Board Examination PYQs (2018-2024)
Q: When the time is 12 noon at 0 degree longitude, the time at 60 degree E longitude will be: (a) 4 p.m. (b) 5 p.m. (c) 3 p.m. (d) 11 p.m.
Official Answer: (a) 4 p.m. [1 Mark]
Q: Write True/False: “The local time of a central meridian of a country is known as the Standard Time.”
Official Answer: True. [1 Mark]
Q: Distinguish between the Equator and the Prime Meridian.
Official Marking Scheme:
• Equator (1.5 Marks): The 0° parallel of latitude; a full circle running horizontally East-West dividing the Earth into Northern and Southern Hemispheres.
• Prime Meridian (1.5 Marks): The 0° meridian of longitude; a semi-circle running vertically North-South passing through Greenwich, dividing the Earth into Eastern and Western Hemispheres.
Frequently Asked Questions (DAV Class 6 SST Ch 3 FAQs)
Q1. Why are latitudes called parallels?
They are called parallels because all lines of latitude run parallel to the Equator and to each other, maintaining a constant equal distance without ever intersecting.
Q2. What is Local Time?
Local Time is the time calculated by the position of the Sun overhead at a given meridian, where 12:00 noon is the moment when the Sun casts the shortest shadow of the day.