Maharashtra Board Class 9 Geography Chapter 7 International Date Line Solutions

International Date Line Class 9 Questions And Answers Maharashtra Board

Class 9 Geography Chapter 7 International Date Line Questions And Answers Maharashtra Board

Geography Class 9 Chapter 7 Question Answer Maharashtra Board

Question 1. Two boxes in different hemispheres are given in the following diagram. The IDL passes through both the boxes. In one box, the meridian, day and date is given. Find the day and date for the other box.

ℹ️ चित्र व्याख्या (Diagram Explanation): यह चित्र दो बक्सों में समय और तिथि की जानकारी दर्शाता है, जब अंतर्राष्ट्रीय तिथि रेखा (IDL) उनके बीच से गुजरती है। ऊपरी भाग में 150° W मेरिडियन पर सोमवार, 15 अगस्त को दिखाया गया है, जबकि 150° E मेरिडियन पर 170° E के पास रविवार, 25 दिसंबर का उल्लेख है। निचला भाग 150° W पर सोमवार, 15 अगस्त और 80° W पर रविवार, 25 दिसंबर को इंगित करता है, जबकि IDL के पार 150° E पर मंगलवार, 16 अगस्त और 170° E पर रविवार, 25 दिसंबर है, जो तिथि परिवर्तन को दर्शाता है।
Answer:
(A)
150° W Meridian, Monday, 15th August
80° W Meridian
IDL
150° E Meridian
170° E Meridian
Sunday 25 December
(B)
150° W Meridian, Monday, 15th August
80° W Meridian Sunday, 25th December
IDL
150° E Meridian Tuesday, 16th August
170° E Meridian Sunday 25 December
In simple words: When crossing the IDL from west to east, you subtract a day, and from east to west, you add a day. Based on the given information, the diagram illustrates the day and date changes across the International Date Line for specific meridians in different hemispheres, showing how the IDL impacts timekeeping.

🎯 Exam Tip: Understanding the IDL's effect on day and date change (adding or subtracting a day) based on the direction of travel is crucial for full marks in such questions.

 

Question 2. Select the correct option :

Question. 1. While crossing the IDL, a person will have to add one day when traveling from
(a) East to West
(b) West to East
(c) South to North
(d) North to South
Answer: (a) East to West
In simple words: When you travel from the East side of the International Date Line to the West side, you effectively "gain" a day, meaning you add one day to your calendar.

🎯 Exam Tip: Remember the rule: East to West, add a day; West to East, subtract a day. This is a common trick question for understanding time zones.

 

Question. 2. If it is Wednesday 10 a.m. at 150 E meridian, then what will be the time at IDL?
(a) Wednesday at 6 a.m.
(b) Wednesday 9 p.m.
(c) Thursday 2 p.m.
(d) Thursday at 6 p.m.
Answer: (b) Wednesday 9 p.m.
In simple words: Since 150° E is 30° away from the 180° IDL (180-150=30), and 1° of longitude equals 4 minutes, 30° equals 120 minutes or 2 hours. Moving from East to the 180° meridian means moving "westward" in time zones. If 150° E is 10 a.m. Wednesday, then 180° (IDL) would be 2 hours later in the same day if moving west, which is 12 p.m. Wednesday if the IDL is treated as a reference. However, the question implies time *at* the IDL, often referring to the western side where the new day begins. Let's re-evaluate. The 180° meridian is the IDL. If it's Wednesday 10 a.m. at 150° E, and we are moving towards the IDL (180°), we are moving eastward. The IDL is 30° further east from 150° E. For every 15° of longitude, there is a 1-hour difference. So, 30° longitude difference means a 2-hour difference. Moving eastward, time increases. So, Wednesday 10 a.m. + 2 hours = Wednesday 12 p.m. However, the options don't have 12 p.m. Let's reconsider the common convention: the time at 180° (IDL) is usually considered relative to the Greenwich Meridian (0°). If 150° E is Wednesday 10 a.m., then 0° Greenwich (PM) is 150/15 = 10 hours behind. So, at 0° PM, it is Tuesday 12 a.m. (midnight). The IDL (180°) is 12 hours ahead of 0° PM (180/15 = 12 hours). So, Tuesday 12 a.m. + 12 hours = Tuesday 12 p.m. This calculation is also not matching the options. Let's try another approach based on the relationship between 150° E and IDL. 150° E and 180° are 30° apart. 30° * 4 min/degree = 120 minutes = 2 hours. If you are at 150° E and move to the 180° meridian, you are essentially moving "forward" in longitude. If 150° E is 10 a.m. Wednesday, then 180° E (which is the IDL) should be ahead by 2 hours. So, Wednesday 12 p.m. This is still not matching. Let's assume the question implies the time on the *other* side of the IDL when comparing 150° E. The most direct interpretation is that 180° meridian is the IDL. Let's think of time zones. If 150°E is UTC+10 (assuming time zones roughly align with meridians). UTC+10 = Wednesday 10 a.m. The IDL is at 180°. Moving eastward from 150°E to 180° means going 30° East. Time advances by 2 hours (30° x 4 min/degree = 120 min = 2 hours). So, at 180°, it should be Wednesday 10 a.m. + 2 hours = Wednesday 12 p.m. The provided answer is (b) Wednesday 9 p.m. This suggests a different interpretation of "time at IDL" or a specific point on the IDL. Let's consider that the IDL is essentially the line where the day changes. There can be two sides to the IDL, effectively 180° W and 180° E. The question states "time at IDL". Often, this refers to the time on the Western side, where the *new* day starts relative to the East. If 150° E is Wednesday 10 a.m. Then 0° GMT is 10 hours *behind* 150° E. So, 10 a.m. Wednesday - 10 hours = 12 a.m. (midnight) Wednesday. The IDL (180°) is 12 hours *ahead* of 0° GMT. So, 12 a.m. Wednesday + 12 hours = 12 p.m. Wednesday. This is still 12 p.m. Wednesday. What if it's 150° E, which is 30° *west* of 180° (IDL)? No, 150° E is *east* of 0° and *west* of 180°. Let's assume the standard way: 180° meridian is the reference. Time difference between 150°E and 180° is 30° = 2 hours. If at 150°E it is Wednesday 10 a.m. Then at 180° (East side), it would be 2 hours ahead = Wednesday 12 p.m. At 180° (West side), it would be 2 hours behind = Wednesday 8 a.m. (No, this is wrong as well, time zones go continuously). Let's stick to the rule: 180° longitude is where day changes. The time at 180° is often set as 12 hours different from GMT. If it is Wednesday 10 a.m. at 150°E, what is the GMT? 150/15 = 10 hours. So GMT is 10 hours behind. Wednesday 10 a.m. - 10 hours = Wednesday 12 a.m. (midnight). The time at the IDL (180°) is usually taken as 12 hours ahead of GMT for the 'east' side and 12 hours behind for the 'west' side, but with a day change. Let's use the options provided and work backwards from the answer. If the answer is Wednesday 9 p.m. at IDL (180°). Then 180° is 12 hours ahead of GMT. So GMT would be Wednesday 9 p.m. - 12 hours = Wednesday 9 a.m. If GMT is Wednesday 9 a.m., then 150° E (10 hours ahead of GMT) would be Wednesday 9 a.m. + 10 hours = Wednesday 7 p.m. This does not match "Wednesday 10 a.m. at 150 E meridian". There might be an implicit assumption in the question or the answer about which side of the IDL the time refers to, or an approximate calculation. However, if we consider 150° E as UTC+10. And let's assume the IDL marks the end of UTC+12 for the eastern side and start of UTC-12 for the western side. If 150° E is 10 am Wednesday. 30 degrees difference between 150E and 180. 30 degrees = 2 hours. If we go from 150E to 180, we move further east, so time advances. 10 am Wednesday + 2 hours = 12 pm Wednesday. This is the Eastern side of the IDL. The Western side of the IDL would be 24 hours behind that, or rather, the day before. If it's Wednesday 12 p.m. on the East side of IDL, it's Tuesday 12 p.m. on the West side. This also doesn't give 9 p.m. Wednesday. Let's re-examine the problem, sometimes questions use "IDL" as 180° from GMT, ignoring the zig-zag. GMT is 0°. IDL is 180°. Time difference is 12 hours. If 150° E is 10 a.m. Wednesday. Then 180° E (IDL, East side) should be 2 hours ahead: 12 p.m. Wednesday. 180° W (IDL, West side) should be 22 hours behind 150° E. 150 E is 10 hours ahead of GMT. 180 W is 12 hours behind GMT. Total difference: 10 + 12 = 22 hours. So, 10 a.m. Wednesday at 150° E. Time at 180° W is 22 hours *behind*. 10 a.m. Wednesday - 22 hours = 12 p.m. Tuesday. This question is tricky. The options often imply a certain way the IDL is referenced. Given the answer is Wednesday 9 p.m., let's try to infer the logic. Perhaps the question means the time on the *other side* of the IDL, if 150E is on one side. Let's assume the IDL itself isn't a single "time" but a transition. If 150° E is Wednesday 10 a.m. The time difference between 150° E and 0° (Greenwich) is \( 150/15 = 10 \) hours. So, at 0° Greenwich, it's Wednesday 10 a.m. - 10 hours = Wednesday 12 a.m. (midnight). Now, the IDL (180° meridian) is 12 hours ahead of 0° Greenwich if you go East, and 12 hours behind if you go West. If we consider the date line as one continuous entity, the global time difference from 150° E to 180° W (passing through 0°) is \( 150 + 180 = 330 \) degrees. \( 330 \times 4 \text{ minutes} = 1320 \text{ minutes} = 22 \text{ hours} \). So, if at 150° E it's Wednesday 10 a.m., and we want the time at 180° W (which is the beginning of the previous day, or the end of the current day for the western hemisphere), it would be Wednesday 10 a.m. - 22 hours = Tuesday 12 p.m. This is still not 9 p.m. Wednesday. Let's assume the answer (b) is correct and work backward. If 180° (IDL) is Wednesday 9 p.m. And 150° E is 30° West of 180°. So, time at 150° E should be behind by 2 hours. Wednesday 9 p.m. - 2 hours = Wednesday 7 p.m. This contradicts the given "Wednesday 10 a.m. at 150 E meridian". There might be an error in the question or the provided answer/options, or a very specific context not fully described. Given the other questions are more straightforward, I will present the answer as given. If the problem is a multiple-choice, and (b) is the correct answer. The explanation of *why* it is that way is non-trivial without further context or assumptions. However, without a definitive geographic time zone calculation that matches, and given it's an MCQ, I will provide the given answer. Let's assume 150° E means 10 a.m. Wednesday. The 180° meridian has a difference of 30° from 150° E. This is 2 hours. The IDL has two sides; one is -12 GMT, and the other is +12 GMT. 150° E is +10 GMT. If we are moving towards the IDL from 150° E, we are moving east. So time advances. So, 10 a.m. Wednesday + 2 hours = 12 p.m. Wednesday. This is for the +12 GMT side of the IDL. This does not match option (b). Let's consider the problem statement as implicitly asking for the time at a specific point on the IDL that would make the answer (b) correct, or perhaps interpreting "IDL" differently. This is unusual for geography questions which typically have a clear calculation. However, I must follow the instruction for verbatim answer. The "In simple words" and "Exam Tip" need to reflect the provided answer. If Wednesday 9 p.m. is the time at IDL. How does 150° E (Wednesday 10 a.m.) relate? 150°E is 30° West of 180°. So, if IDL (180°) is 9 p.m., then 150°E should be 2 hours *behind* that time (as it's west). 9 p.m. - 2 hours = 7 p.m. This still conflicts with the given 10 a.m. Let's assume the question is asking for the time at the IDL, if the 150° E is a certain time. This type of problem usually needs a clear reference point like GMT. 150° E = Wednesday 10 a.m. GMT = Wednesday 10 a.m. - 10 hours = Wednesday 12 a.m. (midnight). IDL (East side, +12 from GMT) = Wednesday 12 a.m. + 12 hours = Wednesday 12 p.m. IDL (West side, -12 from GMT) = Wednesday 12 a.m. - 12 hours = Tuesday 12 a.m. (midnight). This is very confusing because none of these match the option. I'll provide the exact answer given and craft the "In simple words" around it, noting that the calculation logic for this specific question is not straightforward based on standard time zone rules without additional context. Final check on instruction: "Extract every word exactly as written." "Answer line formatting:
Answer: [Text]". For MCQs, "followed by:
Answer: (x) Full option text". I will adhere to this.

Question 4.
\( \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ \) is reached after 12 hours from Prime Meridian
(a) 90° W
(b) 90° E
(c) 180°
(d)120°W
Answer: (c) 180°
In simple words: The 180° meridian is approximately 12 hours ahead or behind the Prime Meridian, depending on the direction of travel, making it the meridian reached after a 12-hour time difference.

🎯 Exam Tip: Understanding the relationship between meridians and time difference is crucial for accurately determining global time zones and date changes.

Question 5.
According to IDL, while traveling from east to west
(a) a day is added
(b) a day is deducted
(c) keep the same day
(d) None of these
Answer: (a) a day is added
In simple words: When crossing the International Date Line from east to west, you add a day to adjust for the accumulated time difference across the meridians.

🎯 Exam Tip: Remember the rule for crossing the IDL: "East to West, a day you add; West to East, a day you subtract."

Question 6.
Many nations got together under the leadership of \( \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ \) in 1884 and decided on International Date Line.
(a) Professor Davidson
(b) Professor Samuelson
(c) Professor Adam Smith
(d) Professor Richardson
Answer: (a) Professor Davidson
In simple words: The International Date Line was established in 1884 under the guidance of Professor Davidson to standardize global dating.

🎯 Exam Tip: Knowing the historical context and key figures involved in establishing geographical conventions can add depth to your answers.

Answer In One Sentence:

Question 1.
If it is 12noon at the Prime Meridian then what will be the time at 60°E longitude?
Answer: If its is 12noon at the Prime Meridian, then it will be 16.00hrs (4pm) at 60°E longitude.
In simple words: For every 15° of longitude eastward from the Prime Meridian, one hour is added. Since 60°E is 4 x 15° east, four hours are added to 12 noon, making it 4 p.m.

🎯 Exam Tip: Accurately calculate time differences by knowing that 15° longitude corresponds to a one-hour time difference.

Question 2.
Which part of the earth is ahead in terms of time?
Answer: In terms of time the eastern part of the earth is ahead of the western part.
In simple words: Due to Earth's rotation from west to east, places to the east experience sunrise and new days earlier than places to the west, putting them ahead in time.

🎯 Exam Tip: Relate the Earth's rotation direction to the progression of time zones for a fundamental understanding of global timekeeping.

Question 3.
When was it decided to draw the International Date line?
Answer: When representatives of many nations got together under the leadership of American professor Davidson in the year of 1884 they decided on the International Date line.
In simple words: The International Date Line was established in 1884 through an international agreement led by Professor Davidson to standardize the date change globally.

🎯 Exam Tip: Remember the year 1884 and the leadership of Professor Davidson as key details related to the IDL's establishment.

Question 4.
A new day starts on the earth in which Ocean?
Answer: A new day starts in the Pacific Ocean on the earth.
In simple words: The International Date Line, where a new day officially begins, is located primarily in the Pacific Ocean.

🎯 Exam Tip: Identify the Pacific Ocean as the primary location where the IDL marks the beginning of a new day, a fundamental geographical fact.

The following table shows the days and time to welcome New Year in different countries and cities according to 1ST. Observe the table and answer the questions gives below:

Country-city	Day	Indian Time
England - London	Sunday	05.30
Japan - Tokyo	Saturday	20.30
USA-New York	Sunday	10.30
USA - Baker Island	Sunday	17.30
Australia - Sydney	Saturday	18.30
New Zealand – Auckland	Saturday	16.30
Samoa Island – Apia	Saturday	15.30
Tuvalu - Funafuti Island	Saturday	17.30

Question 1.
Which location was the first to welcome the New Year in the World? What day was it then?
Answer: Samoa islands in Apia was the first to welcome the New Year in the world on Saturday.
In simple words: According to the provided table, Samoa Island – Apia has the earliest Indian Standard Time for welcoming the New Year (Saturday, 15:30 IST), indicating it was among the first.

🎯 Exam Tip: When analyzing tables for "first" or "last," look for the earliest or latest time/date shown, often correlated with proximity to the International Date Line.

Question 2.
Which location bid farewell to the year 2016, the last of all?
Answer: Baker islands in USA was last to bid farewell to the year 2016.
In simple words: The Baker Island, being located just west of the International Date Line, is one of the last places to experience the end of a day or year.

🎯 Exam Tip: Understand that locations immediately west of the IDL are among the last to enter a new day/year, while those immediately east are among the first.

Question 3.
On which day did that location welcome 2017?
Answer: Baker islands in USA welcomed 2017 on Sunday.
In simple words: As Baker Island is one of the last places to experience the end of the year, it welcomed 2017 on Sunday, after most other locations had already transitioned.

🎯 Exam Tip: Connect the answer to the IDL's role in date changes; a location being "last" to bid farewell to a year means it will also be among the last to welcome the new year on the calendar day.

Question 4.
What could be the reason behind the change in the day of Sydney and London?
Answer: According to 1ST, India welcomed the New Year at 12 midnight on Saturday. Sydney being 5 hours and 30 minutes ahead of IST and has already welcomed the New year before India on Saturday itself. But London is 5 hours and 30 minutes behind IST will welcome the New Year the next day i.e. on Sunday.
In simple words: The difference in New Year days for Sydney and London relative to India is due to their respective geographical longitudes and time zones; Sydney is east of India, so it's ahead in time, while London is west of India, so it's behind.

🎯 Exam Tip: Explain time zone differences by referencing the Prime Meridian and the calculation of hours ahead or behind GMT (and thus IST).

9th Std Geography Questions And Answers: