Page 80 - Mathematics Class - IX

Viva-Voce

1. What is the formula for finding the surface area of a sphere?

Ans. 4pr 2
2. What is hemisphere?
Ans. The equal half part of sphere is called a hemisphere.

3. Is sphere a two-dimensional figure?
Ans. No, sphere is a three-dimensional figure.
4. Are the total surface area and curved surface area of a sphere equal?

Ans. Yes
5. Can we take a CD as an example of a sphere?
Ans. No

6. What is the volume of sphere?
4
Ans. πr 3
3

MCQs

1. A sphere is a _______________ dimensional figure.

a) One b) Two c) Three d) Four
2. The formula for area of a circle is
a) pr b) 2 pr c) 1/2pr 2 d) pr 3
2
2
3. If the radius of circle and a sphere is same, what will be the ratio of the area of circle to the surface area of
the sphere?

a) 1 : 2 b) 2 : 3 c) 1 : 3 d) 1 : 4
4. Which of the following is not an example of sphere?

a) Volleyball b) Earth c) Marble d) Football
5. A sphere has
a) 4 edges b) only one curved surface
c) two surfaces d) base with slant height
6. If the surface area of sphere is 1386 cm , then find the radius of the sphere.
2
a) 12.5 cm b) 10.5 cm c) 10 cm d) 12 cm
7. A copper sphere of diameter 18 cm is drawn into a wire of diameter 6 mm, then the length of wire will be
a) 143 m b) 108 m c) 324 m d) 234 m

Answers: 1. c) Three 2. a) pr 3. d) 1 : 4 4. b) Earth
2
5. b) Only one curved surface 6. b) 10.5 cm 7. b) 108 m

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