ose and write the correct option in the following questions. 1. The radius of a sphere is 2r, then its volume will be [NCERT Kxemplar 4 ) bx ()) An? © fxr w Ba d and recast into a sphere. 2. Aconeis 8.4 cm high and the radius of its base is 2.1 cm. It is meltec ‘The radius of the sphere is (©) 24cm (d) 16am (a) 4.2cm (b) 2... cm (NCERT Exemplar\3. The ratio of surface area and volume of the sphere of unit radius is (a) wa oa wis ‘The height of a cone is 16 em and base radius is 12 em Hs slant height is 2 8 (@) Wem (b) 15 em (©) 206m (d) 8cm ist ant height 21 i 5. The total surface area ofa cone whose radius is 5 and slant height 2/is (©) 2m @ m{t+4) (@) Band +7) () ml +7) ‘The radius of a hemispherical balloon increases from 6 em to 12 em as being pumped as of the balloon in the two cases is (NCERT Exempp) (2:1 into it, The ratios of the surface area @) 1s Oe 7. Volume ofa hemisphere is 19404 em’ (2:3 °, The total surface area is (a) 2772 cm? (b) 4158 cm? (© 5544 cm? (d) 1346 cm? A spherical lead ball of radius 8 cm is melted and small lead balls of radius 16 mm are made, ‘The total number of possible small lead balls is (a) 250 (b) 125 (c) 400 @) 1250 9. The capacity in litres of a conical vessel with radius 7 em and slant height 25 cm is (@) 24641 (6) 3.396 L © 1232L (@) 0.2464 L 10. The diameter of the base of a cone and its slant height are 10.5 cm and 10 cm respectively. Its curved surface area is (@) 330 cm? (®) 165 cm® (©) 150 cm? (d) None of these 11. If the ratio of the surface area of two spheres is 9:16, then ratio of their volumes is (a) 9:16 (b) 27:48 (c) 27 : 64 @) 81: 256 12. The height of a cone with radius 10 cm and slant height 26 cm is (a) 26cm () 16 cm © 20cm @) 24cm 13. If the radius of a right circular cone is 'r' em and its height is thrice the radius, then its slant height is (@) ¥I0 rem (b) rem (©) 2rem @) v2rem 14. The area of sheet required to cover a hemispherical bowl of radius 20 cm is (@) 800x cm? (®) 12007 cm? (©) 1600n cm? (@) 800x cm? 15. The surface area of a spherical ball is 5544 cm’. Its diameter is (@) 21cm C) a cm (©) 42cm (@) 63 cm 16. The curved surface area of a cone is 2200 cm’. Ifits radius is 20cm, then the length of its slant height is (@) 35cm () 30 cm (© 15cm @ 25cm| | ] | | | | | | } MBBS ee 2D representation of a figure Is given below, rhe 2 expressions represent the curved surface which of these area of the figure? [Competency Hased Question} dem 16m Sem Fig. 14.7 () nx 4m x 15cm (2) 2x nx 4m x (4m + 15cm) rrect net of the right circular cone whose total surface area is [Competency Based Question) ay ex chem +15 em) x dem x (dem + 15 em) or i Which of these represents the co gort4 feet”? 0) ton tor 0 a Bt an oO qd) of rice is in the form of a cone whose diameter is 4.2 m and height is 2.8 m. The heap Aheap anys covered exactly by a canvas to protect it from rain. Ifthe rate of the canvas is €3 per my ‘chat is the total cost of the canvas needed to cover the heap? [CBSE Question Bank] (a) % 42.3 (6) % 69.3 (c) & 82.53 @ 7142.3 Rakesh is building a birdhouse. The roof of the birdhouse is in the form of a right circular cone whose radius is 21 em and slant height is 47 cm. He plans to paint the roof red, but he seeds to know the surface area to buy the right amount of paint. What is the surface area of the roof, including the bottom? [Competency Based Question} (a) 4488 cm? (b) 4848 cm? (©) 5261 cm? (@) 6218 cm? |. A hemispherical bowl made of brass has inner radius 5.25 em, What is the total cost of tin- plating it on the inside at the rate of €4 per em®? (CBSE Question Bank] (o) 769.3 (&) % 693 (© € 6,930 @) % 69,300 Ahemispherical dome of a tomb needs to be painted. The circumference of the base of the dome is 17.6 cm. If the cost of painting is ¥ 7 per cm”, what is the cost, rounded to the nearest 22 rupee, to paint the dome? (use 7 for x) [CBSE Question Bank] (a) 390 (b) 345 () = 571 @d) % 690can a conic 28. How many cubie centimeters of wal height 29 em hold? (a) 814 em (Ome 24. The radius and height ofa conical cup is in which of these can be slant height of the cone, (o) 9,240 em? eee the ratio 3:4. Ifthe volume of the cup is 2.376 rounded off to the nearest whole numbers (CBSE Question Bang (0 20cm Onan s completely filed with milk. How many fines 9 4cm* cm’, (@) 4em ()) 16cm 25. A hemispherical bowl of diameter 21 em i 22 milk, to the nearest tenth, is contained in the bowl? (use 7 for x) (CBSE Quetion Bay (b) 2.4 (c) 3.4 (d) 4.4 (a) 14 melted to form 3 identical big hemisphe res, 26. Fifteen metallic hemispheres of radius 4.5 cm are Ifthe density of the metal is 8.5 g/em’, what is the mass of a bigger hemisphere? (Use 2 na 7 [Competency Based Question (@) 8114.46 g (6) 2,165.15 g (©) 8,130.63 g @) 8,138.75 g