ML Aggarwal Solution Class 10 Chapter 17 Mensuration MCQs
MCQs
Question 1
In a cylinder, if radius is halved and height is doubled then the volume will be
(a) same
(b) doubled
(c) halved
(d) four times
Sol :
Let radius of cylinder = r
and height = h
then volume = πr²h
If the radius is halved and the height is doubled
=πr24×2h=12(πr2h)
which is half
Ans (c)
Question 2
In a cylinder, if the radius is doubled and height is halved then its curved surface area will be
(a) halved
(b) doubled
(c) same
(d) four times
Sol :
Let radius of a cylinder = r
and height = h
Then curved surface area = 2πrh
Now if radius is doubled and height is halved,
Question 3
If a well of diameter 8 m has been dug to the depth of 14 m, then the volume of the earth dug out is
(a) 352 m3
(b) 704 m3
(c) 1408 m3
(d) 2816 m3
Sol :
Diameter of a well = 8 m
Depth (h) = 14 m
Volume of the earth dug put = πr2h
Question 4
If two cylinders of the same lateral surface have their radii in the ratio 4 : 9, then the ratio of their heights is
(a) 2 : 3
(b) 3 : 2
(c) 4 : 9
(d) 9 : 4
Sol :
Ratio in two cylinder having same lateral surface area their radii is 4 : 9
Let r1 be the radius of the first and r2 be the second cylinder
and h1,h2 and their heights
∴2πr1h1=2πr2h2
=2π4x×h1=2×π×9xh2
h1h2=9x4x=9:4
Ratio in their heights = 9 : 4
Ans (d)
Question 5
The radii of two cylinders are in the ratio 2 : 3 and their heights are in the ratio 5 : 3. The ratio of their volumes is
(a) 10 : 17
(b) 20 : 27
(c) 17 : 27
(d) 20 : 37
Sol :
Radii of two cylinder are in the ratio = 2 : 3
Let radius (r1) = 2x
and radius (r2) = 3x
Ratio in their height = 5 : 3
Let height of the first cylinder = 5y
and of second = 3y
Now, volume of the first cylinder
and volume of second =π(3x)2×3y
=π×27x2y
∴ Ratio is 20πx2y:27πx2y
=20:27
Ans (b)
Question 6
The total surface area of a cone whose radius is r2 and slant height 2l is
(a) 2πr (l + r)
(b) πr(l+r4)
(c) πr(l + r)
(d) 2πrl
Radius of a cone =r2
and slant height = 2l
total surface area of a cone
Question 7
If the diameter of the base of cone is 10 cm and its height is 12 cm, then its curved surface area is
(a) 60π cm2
(b) 65π cm2
(c) 90π cm2
(d) 120π cm2
Sol :
Diameter of the base of a cone = 10 cm
and height (h) = 12 cm
Curved surface area
=πrl=π×5×13=65πcm2
Ans (b)
Question 8
If the diameter of the base of a cone is 12 cm and height is 20 cm, then its volume is ,
(a) 240π cm3
(b) 480π cm3
(c) 720π cm3
(d) 960π cm3
Sol :
Diameter of the base of a cone = 12 cm
and height (h) = 20 cm
=240πcm3
Ans (a)
Question 9
If the radius of a sphere is 2r, then its volume will be
Sol :
Radius of a sphere = 2r
Question 10
If the diameter of a sphere is 16 cm, then its surface area is
(a) 64π cm2
(b) 256π cm2
(c) 192π cm2
(d) 256 cm2
Sol :
Diameter of a sphere = 16 cm
Surface area =4π2=4π×8×8 cm2=256πcm2
Ans (b)
Question 11
If the radius of a hemisphere is 5 cm, then its volume is
Question 12
If the ratio of the diameters of the two spheres is 3 : 5, then the ratio of their surface areas is
(a) 3 : 5
(b) 5 : 3
(c) 27 : 125
(d) 9 : 25
Sol :
Ratio in the diameters of two spheres = 3 : 5
Let radius of the first sphere = 3x cm
and radius of the second sphere = 5x cm
Ratio in their surface area
Ans (d)
Question 13
The radius of a hemispherical balloon increases from 6 cm to 12 cm as air is being pumped into it. The ratio of the surface areas of the balloon in the two cases is
(a) 1 : 4
(b) 1 : 3
(c) 2 : 3
(d) 2 : 1
Sol :
Radius of balloon (hemispherical) in the original position = 6 cm
and in increased position = 12 cm
Ratio in their surface areas
Question 14
Question 15
Question 16
Question 17
Question 18
Question 19
Question 20
Question 21
∴ Ratio is 16: 9
Ans (d)
Question 22
If a cone, a hemisphere and a cylinder have equal bases and have same height, then the ratio of their volumes is
(a) 1 : 3 : 2
(b) 2 : 3 : 1
(c) 2 : 1 : 3
(d) 1 : 2 : 3
Sol :
If a cone, a hemisphere and a cylinder have equal bases = r (say)
and height = h in each case and r = h
=13πr2r:23πr3:πr2r
=13πr3:23πr3:πr3
=13:23:1=1:2:3
Ans (d)
Question 23
If a sphere and a cube have equal surface areas, then the ratio of the diameter of the sphere to the edge of the cube is
(a) 1 : 2
(b) 2 : 1
(c) √π : √6
(d) √6 : √π
Sol :
A sphere and a cube have equal surface area
Let a be the edge of a cube and r be the radius of the sphere, then
Question 24
A solid piece of iron in the form of a cuboid of dimensions 49 cm x 33 cm x 24 cm is moulded to form a sphere. The radius of the sphere is
(a) 21 cm
(b) 23 cm
(c) 25 cm
(d) 19 cm
Sol :
Dimension of a cuboid = 49 cm × 33 cm × 24 cm
Volume of a cuboid = 49 × 33 × 24 cm3
⇒ Volume of sphere = Volume of a cuboid
Volume of a sphere = 49 × 33 × 24 cm3
=(49×33×24×3×74×22)13
=(49×7×3×3×3)13
=(7×7×7×3×3×3)13
=7×3=21 cm
Ans (a)
Question 25
If a solid right circular cone of height 24 cm and base radius 6 cm is melted and recast in the shape of a sphere, then the radius of the sphere is
(a) 4 cm
(b) 6 cm
(c) 8 cm
(d) 12 cm
Sol :
Height of a circular cone (h) = 24 cm
and radius (r) = 6 cm
Volume of sphere=Volume of a cone
Now volume of sphere =13π×36×24 cm3
Let r be in radius of sphere
Then 43πr3=13π×36×24
4r3=36×24⇒r3=36×244
r3=3×3×3×2×2×2=33×23
∴r=3×2∘=6 cm
Ans (b)
Question 26
If a solid circular cylinder of iron whose diameter is 15 cm and height 10 cm is melted and recasted into a sphere, then the radius of the sphere is
(a) 15 cm
(b) 10 cm
(c) 7.5 cm
(d) 5 cm
Sol :
Diameter of a cylinder = 15 cm
and height = 10 cm
=1125π2 cm3
∴ Volume of sphere =1125π2 cm3
∴ Radius of sphere =( Volume 43π)13
=(1125π×32×4π)13=(33758)13
=(1125π×32×4π)13=(33758)13
333753112533755125525551
=(53×3323)13=5×32 cm
=152=7.5 cm
Ans (c)
Question 27
The number of balls of radius 1 cm that can be made from a sphere of radius 10 cm is
(a) 100
(b) 1000
(c) 10000
(d) 100000
Sol :
Radius of sphere (R) = 10 cm
Question 28
Question 29
Question 30
Radius =22=1 cm
and height = 16 cm
=227×1×1×16=3527 cm3
∴ Volume of 12 solid spheres so formed
=3527 cm3
∴ Volume of each sphere =3527×12=35284 cm3
∴ Radius of each sphere =(352×3×784×4×22)13
=(1)13=1 cm
∴ Diameter =2×1=2 cm
Ans (c)
Question 31
A hollow cube of internal edge 22 cm is filled with spherical marbles of diameter 0.5 cm and it is assumed that 18 space of the cube remains unfilled. Then the number of marbles that the cube can accommodate is
(a) 142296
(b) 142396
(c) 142496
(d) 142596
Sol :
Internal edge of a hollow cube = 22 cm
Diameter of spherical marble =0.5 cm=12
∴ Radius =12×12=14 cm
∴ Volume =43πr3
=43×227×14×14×14 cm3
=11168 cm3
Space left unfilled =10648×18 cm3
=1331 cm3
∴ Remaining volume for marbles
=10648−1331=9317 cm3
∴ Number of marble to accommodate
=9317÷11168=9317×16811
=142296
Ans (a)
Question 32
In the given figure, the bottom of the glass has a hemispherical raised portion. If the glass is filled with orange juice, the quantity of juice which a person will get is
(a) 135 π cm3
(b) 117 π cm3
(c) 99 π cm3
(d) 36 π cm3
and height (h)= 15 cm
=πr(rh−23r2)
=π×3(3×15−23×9)
=3π(45−6)cm3
=3π×39=117πcm3
Ans (b)
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