NCERT Solutions for Class 9 Maths Chapter 13 Surface Areas and Volumes Ex 13.8

NCERT Solutions for Class 9 Maths Chapter 13 Surface Areas and Volumes Ex 13.8 are part of NCERT Solutions for Class 9 Maths. Here we have given NCERT Solutions for Class 9 Maths Chapter 13 Surface Areas and Volumes Ex 13.8.

• Surface Areas and Volumes Class 9 Ex 13.1
• Surface Areas and Volumes Class 9 Ex 13.2
• Surface Areas and Volumes Class 9 Ex 13.3
• Surface Areas and Volumes Class 9 Ex 13.4
• Surface Areas and Volumes Class 9 Ex 13.5
• Surface Areas and Volumes Class 9 Ex 13.6
• Surface Areas and Volumes Class 9 Ex 13.7
• Surface Areas and Volumes Class 9 Ex 13.8
• Surface Areas and Volumes Class 9 Ex 13.9

Board	CBSE
Textbook	NCERT
Class	Class 9
Subject	Maths
Chapter	Chapter 13
Chapter Name	Surface Areas and Volumes
Exercise	Ex 13.8
Number of Questions Solved	10
Category	NCERT Solutions

NCERT Solutions for Class 9 Maths Chapter 13 Surface Areas and Volumes Ex 13.8

Assume π = unless stated otherwise.
Question 1.
Find the volume of a sphere whose radius is
(i)  7 cm
(ii) 0.63 m
Solution.
(i) We have, r = 7 cm

Question 2.
Find the amount of water displaced by a solid spherical ball of diameter.
(i) 28 cm
(ii) 0. 21
Solution.

Question 3.
The diameter of a metallic ball is 4.2 cm. What is the mass of the ball, if the density of the metal is 8.9 g per cm³?
Solution.

Question 4.
The diameter of the Moon is approximately one-fourth of the diameter of the Earth. What fraction of the volume of the Earth is the volume of the Moon?
Solution.
Let diameter of the Earth be d₂.
According to the question,

Question 5.
How many liters of milk can a hemispherical bowl of diameter 10 cm hold?
Solution.

Question 6.
A hemispherical tank is made up of an iron sheet 1 cm thick. If the inner radius is 1 m, then find the volume of the iron used to make the tank.
Solution.

Question 7.
Find the volume of a sphere whose surface area is 154 cm².
Solution.

Question 8.
A dome of a building is in the form of a hemisphere. From inside, it was white-washed at the cost of Rs. 498.96. If the cost of white-washing is Rs. 2.00 per sq m, then find the
(i) inside surface area of the dome,
(ii) volume of the air inside the dome.
Solution.
Given, Cost of white – Washed = Rs. 498.96
and cost of whitewashed per sq.m = Rs. 2.00

Question 9.
Twenty seven solid iron spheres, each of radius r and surface area S are melted to form a sphere with surface area S’. Find the
(i) radius r’ of the new sphere,
(ii) ratio of S and S’.
Solution.

Question 10.
A capsule of medicine is in the shape of a sphere of diameter 3.3. How much medicine (in mm³) is needed to fill this capsule?
Solution.

 

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