Page 77 - Mathematics Class - IX

Viva-Voce

1. What kind of a solid is generated when a rectangle is rotated along any of its dimension?
Ans. A cylinder.
2. Define a right-circular cylinder.
Ans. A cylinder in which the axis/height is perpendicular to the radius of its base is called a right-circular cylinder.

3. How much area is covered by a cylinder in a revolution with radius ‘r’ and height ‘h’?
Ans. One revolution will cover curved surface area = 2prh.
4. Write the formula for surface area of a cylinder with an open top.
Ans. 2prh + pr 2

5. Write the formula for total surface area of a cylinder.
Ans. 2prh + 2pr or 2pr (h + r)
2
6. What is the volume of right circular cylinder?
Ans. pr h
2
7. How many vertices does a cylinder have?
Ans. No
8. How many bases does the cylinder have?
Ans. Two circular bases.

MCQs

1. Curved surface area of a cylinder is 308 cm and the height is 14 cm. What will be the volume of the
2
cylinder?
a) 439 cm b) 385 cm c) 539 cm d) 529 cm 3
3
2
3
2. The curved surface area of a cylinder of height 14 cm is 88 sq. cm. The diameter of the cylinder is
a) 0.5 cm b) 1 cm c) 1.5 cm d) 2 cm
3. The total surface area of a right circular cylinder of diameter 42 cm and height 14 cm is

a) 4488 cm b) 4250 cm c) 4010 cm d) none of the above
2
2
2
4. In a cylinder, radius is doubled and height is halved, the curved surface area will be
a) halved b) doubled c) same d) four times
5. The curved surface area of a cylinder with radius 7 cm and height 16 cm is
a) 470 cm b) 407 cm c) 740 cm d) 704 cm 2
2
2
2
Answers: 1. c) 539 cm 2. d) 2 cm 3. d) none of the above
3
4. c) same 5. d) 704 cm 2

75