NCERT Solutions Ganita Prakash Chapter 10 Geographical cross sections — Figure it Out
Book page 261 Updated on2026-09-05
Q1.
Looking at the geographical cross section, fill in the respective heights: a. b. c. d. e. f. g.
Answer
Read each marked point against the height scale on the left. Sea level is 0 m; above it the heights are positive, below it they are negative.
The geographical cross section with the seven points read off the height scale. Peaks are positive, valleys and ocean floors are negative.
Point
a. A
b. B
c. C
d. D
e. E
f. F
g. G
Height
+ 1500 m
– 500 m
+ 300 m
– 1200 m
+ 1200 m
– 200 m
+ 100 m
Tip: These are readings from a drawing, so answers a little different from these (say + 1450 m for A) are also acceptable — what matters is the sign and the rough size.
Q2.
Which is the highest point in this geographical cross section? Which is the lowest point?
Answer
Highest: A, at + 1500 m above sea level Lowest: D, at – 1200 m below sea level
A is the tallest peak in the slice, and D is the deepest trench.
Why D and not B: both are below sea level, but – 1200 < – 500. With negative numbers the one further from 0 is the smaller — and here it is also the deeper one.
Q3.
Can you write the points A, B, …, G in a sequence of decreasing order of heights? Can you write the points in a sequence of increasing order of heights?
Answer
List the seven heights: + 1500, – 500, + 300, – 1200, + 1200, – 200, + 100.
Decreasing order: A (+ 1500) > E (+ 1200) > C (+ 300) > G (+ 100) > F (– 200) > B (– 500) > D (– 1200)
Increasing order: D (– 1200) < B (– 500) < F (– 200) < G (+ 100) < C (+ 300) < E (+ 1200) < A (+ 1500)
Tip: Sort the positive heights normally, sort the negative heights in the reverse way, and remember that every positive height beats every negative one.
Q4.
What is the highest point above sea level on Earth? What is its height?
Answer
The highest point on Earth is Mount Everest (Sagarmatha / Chomolungma), in the Himalayas on the Nepal–China border.
Height of Mount Everest = + 8848 m above sea level (the 2020 joint survey by India's neighbours put it at 8848.86 m)
Did you know? India's highest peak is Kangchenjunga in Sikkim, at + 8586 m — the third highest mountain in the world.
Q5.
What is the lowest point with respect to sea level on land or on the ocean floor? What is its height? (This height should be negative).
Answer
The lowest point anywhere on Earth is the Challenger Deep, at the southern end of the Mariana Trench in the Pacific Ocean.
Depth of the Challenger Deep ≈ – 11 000 m (about – 10 935 m)
On land, the lowest exposed point is the shore of the Dead Sea, at about – 430 m.
Why the height is written as negative: heights are measured from sea level, which is 0 m. Anything below that mark gets a minus sign, just like the basement floors of Bela's building.
Compare: Everest is + 8848 m and the Challenger Deep is about – 11 000 m. The difference between them is 8848 + 11 000 = 19 848 m — nearly 20 km from the top of the world to the bottom!