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.
**Ex 13.8 Class 9 Maths 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

Ex 13.8 Class 9 Maths Question 2.

Find the amount of water displaced by a solid spherical ball of diameter.

(i) 28 cm

(ii) 0. 21

Solution.

Ex 13.8 Class 9 Maths 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 cm^{3}?

Solution.

Ex 13.8 Class 9 Maths 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 d_{2}.

According to the question,

Ex 13.8 Class 9 Maths Question 5.

How many liters of milk can a hemispherical bowl of diameter 10 cm hold?

Solution.

Ex 13.8 Class 9 Maths 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.

Ex 13.8 Class 9 Maths Question 7.

Find the volume of a sphere whose surface area is 154 cm^{2}.

Solution.

Ex 13.8 Class 9 Maths 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

Ex 13.8 Class 9 Maths 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.

Ex 13.8 Class 9 Maths Question 10.

A capsule of medicine is in the shape of a sphere of diameter 3.3. How much medicine (in mm^{3}) is needed to fill this capsule?

Solution.

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