Page 1 : MATHEMATICS - x, , 14.28, i i in di t be taken to recast into a, 5. What length of a solid cylinder 2 cm in diameter mus’ e, hollow a of length 16 cm, external diameter 20 cm and thickness 2.5 min ., 1 to its height is full of water which is, , 6. A cylindrical vessel having diameter equa I 1, eee into two identical cylindrical vessels with diameter 42 cm and height 21 cm, which are filled completely. Find the diameter of the cylindrical vessel., , 7. 50 circular plates each of diameter 14 cm and thickness 0.5 cm are placed one above, the other to form a right circular cylinder. Find its total surface area., , 8. 25 circular plates, each of radius 10.5 cm and thickness 1.6 cm, are placed one above, the other to form a solid circular cylinder. Find the curved surface area and the, volume of the cylinder so formed., , 9. Find the number of metallic circular discs with 1.5, 0.2 cm to be melted to form a right circular cylinder of hei, 45cm., , 10. How many spherical lead shots e, rectangular lead piece with dimensions 66 cm x 42 cm x 21 cm., [NCERT EXEMPLAR], , e out of a solid cube of, [NCERT EXEMPLAR], , cm base diameter and of height, ight 10 cm and diameter, [NCERT EXEMPLAR], , ach of diameter 4.2 cm can be obtained from a solid, , 11. How many spherical lead shots of diameter 4 cm can be madi, lead whose edge measures 44 cm., 12. Three cubes of a metal whose edges are in the ratio 3: 4: 5are melted and converted, into a single cube whose diagonal is 12/3 em. Find the edges of the three cubes., [NCERT EXEMPLAR], 13. A solid metallic sphere of radius 10.5 cm is melted and recast into a number of smaller, cones, each of radius 3.5 cm and height 3 cm. Find the number of cones so formed., , [CBSE 2017, NCERT EXEMPLAR], , 14. The diameter of a metallic sphere is equal to 9 cm. It is melted and drawn into a long wire, of diameter 2 mm having uniform cross-section. Find the length of the wire., , 15. Aniron spherical ball has been melted and recast into smaller balls of equal size. If the, radius of each of the smaller balls is 1/4 of the radius of the original ball, how many such, balls are made? Compare the surface area, of all the smaller balls combined together, with that of the original ball, , 16. A copper sphere of radius 3. cm is melted and recast into a right circular cone of height 3, cm. Find the radius of the base of the cone., , 17. A copper rod of diameter 1 cmand length 8 cm is drawn into a wire of length 18 m of, uniform thickness. Find the thickness of the wire. [NCERT], , 18. The diameters of internal and external surfaces of a hollow spherical shell are 10 cmand, 6 cm respectively. If it is melted and recast into a solid cylinder of length of, , Z 2 j, ae cm, find the diameter of the cylinder, , 19. How many coins 1.75 cm in diameter and 2 mm thick must be melted to form a, cuboid 11 cm x 10 cm x 7 cm? [NCERT], , 20. The surface area of a solid metallic 5 i 2. i, 1 : phere is 616 cm’. It is melted and recast, a, aes height 28 cm. Find the diameter of the base of the cone so formed., n = 22/7). [CBSE 2010]