(i) Express 5 cm in meter and kilometer.
∵ 100 cm = 1 meter
∴ 1 cm = 1/100 meter
⇒ 5 cm = 5/100 = 0.05 meter.
Now,
∵ 1000 meters = 1 kilometers
∴ 1 meter = 1/1000 kilometers
0.05 meter = 0.05/1000 = 0.00005 kilometer

(ii) Express 35 mm in cm, m and km.
∵ 10 mm = 1 cm
∴ 1 mm = 1/10 cm
⇒ 3.5 cm = 3.5/100 = 0.035 meter
Again,
∵ 1000 meters = 1 kilometers
∴ 1 meter = 1/1000 kilometer
⇒ 0.035 meter = 0.035/1000 = 0.000035 kilometer

Class 7 Maths Chapter 2 Exercise 2.5 Question 3, 4

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https://www.tiwariacademy.com/ncert-solutions/class-7/maths/chapter-2/