# RD SHARMA Solutions for Class 9 Maths Chapter 21 - Surface Areas and Volume of a Sphere

Page / Exercise

## Chapter 21 - Surface Areas and Volume of a Sphere Exercise Ex. 21.1

Solution 1 Solution 2 Solution 3 Solution 4 Solution 5 Solution 6 Solution 7 Solution 8  Solution 9 Solution 10 Solution 11  Solution 12  Solution 13 ## Chapter 21 - Surface Areas and Volume of A Sphere Exercise Ex. 21.2

Solution 1 Solution 2 Solution 3 Solution 4 Solution 5 Solution 6 Solution 7 Solution 8 Solution 9 Solution 10 Solution 11 Solution 12 Solution 13 Solution 14 Solution 15 Solution 16 Solution 17 Solution 18 Solution 19 Solution 20 Solution 21 Solution 22
Inner radius (r1) of hemispherical tank  = 1 m
Thickness of hemispherical tank       = 1 cm = 0.01 m
Outer radius (r2) of hemispherical tank = (1 + 0.01) m = 1.01 m
Volume of iron used to make the tank  =  Solution 23
Radius (r) of capsule Volume of spherical capsule  Thus, approximately 22.46 mm3 of medicine is required to fill the capsule.

Solution 24
Let diameter of earth be d. So, radius earth will be .
Then, diameter of moon will be . So, radius of moon will be .
Volume of moon = Volume of earth =  Thus, the volume of moon is of volume of earth.

Solution 25 Solution 26 Solution 27 Solution 28 Solution 29 Solution 30 Solution 31 Solution 32 ## Chapter 21 - Surface Areas and Volume of a Sphere Exercise 21.26

Solution 1

Sphere has only one surface i.e. curved surface, so number of faces = 1

Hence, correct option is (a).

Solution 2

A hemisphere has two surfaces: one top surface and other curved surface.

T.S.A. = 2∏r2 + (∏r2)   {Area of Top-face = ∏r2}

= 3∏r2

Solution 3 Solution 4 Solution 5 Solution 6 Solution 7 Solution 8 Solution 9 ## Chapter 21 - Surface Areas and Volume of a Sphere Exercise 21.27

Solution 10  Solution 11 Solution 12 Sphere touches cylinder at Top, Base and Lateral Surface.

Then,

2r = height of cylinder = h

Volume of cylinder = ∏r2h

=∏r2(2r)

= 2∏r3

Hence, correct option is (c).

Solution 13 Solution 14  Solution 15  ### STUDY RESOURCES

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