13. Surface Areas and Volumes Class 9 Mathematics NCERT Exemplar Solutions (CBSE)

Chapter 13: Surface Areas and Volumes – Class 9 Mathematics NCERT Exemplar Solutions (CBSE Board)

Chapter 13: Surface Areas and Volumes

EXERCISE 13.1
Write the correct answer in each of the following :
1. The radius of a sphere is 2r, then its volume will be
(A) 43πr³ (B) 4πr³ (C)  83πr³    (D) 323πr³
2. The total surface area of a cube is 96 cm²  . The volume of the cube is:
(A) 8 m³  (B) 512 m³   (C) 64 m³  (D) 27 m³ 
3. A cone is 8.4 cm high and the radius of its base is 2.1 cm. It is melted and recast into a sphere. The radius of the sphere is :
(A) 4.2 cm (B) 2.1 cm (C) 2.4 cm (D) 1.6 cm
4. In a cylinder, radius is doubled and height is halved, curved surface area will be

(A) halved (B) doubled (C) same (D) four times
5. The total surface area of a cone whose radius is  r2  and slant height 2l is
(A)  2πr(l+r)   (B)   πr(l+4r )    (C)  πr(l+r) (D) 2πrl
6. The radii of two cylinders are in the ratio of 2:3 and their heights are in the ratio of 5:3. The ratio of their volumes is:
(A) 10 : 17 (B) 20 : 27 (C) 17 : 27 (D) 20 : 37
7. The lateral surface area of a cube is 256 ² . The volume of the cube is
(A) 512 m³    (B) 64 m³ (C) 216 m³ (D) 256 m³ 
8. The number of planks of dimensions (4 m × 50 cm × 20 cm) that can be stored in a pit which is 16 m long, 12m wide and 4 m deep is
(A) 1900 (B) 1920 (C) 1800 (D) 1840
9. The length of the longest pole that can be put in a room of dimensions (10 m × 10 m × 5m) is
(A) 15 m (B) 16 m (C) 10 m (D) 12 m
10. The radius of a hemispherical balloon increases from 6 cm to 12 cm as air is being pumped into it. The ratios of the surface areas of the balloon in the two cases is
(A) 1 : 4 (B) 1 : 3 (C) 2 : 3 (D) 2 : 1

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Posted 4 months ago