# Geotechnical Engineering Questions and Answers – Particle Size Distribution Curve

This set of Geotechnical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Particle Size Distrubution Curve”.

1. A soil sample may be well graded if __________
a) If it has most number of particles of same size
b) Excess of certain particles
c) Good representation of particles of all size
d) None of the mentioned

Explanation: A soil is said to be well graded when it has a good representation of particle of all size.

2. For coarse grained soil, the particle size D10 is sometimes called as __________
a) Effective size and effective diameter
b) Uniform diameter
c) All of the mentioned
d) None of the mentioned

Explanation: The size D10 is sometimes called as the effective size or effective diameter.

3. The shape of particle size curve, which is represented by the coefficient of curvature (Cc) is given by __________
a) Cc = (D30)2/D10×D40
b) Cc = (D40)2/D10×D30
c) Cc = (D30)2/D10×D60
d) Cc = D60/D10

Explanation: The coefficient of curvature (Cc) is given by the equation
Cc = (D30)2/D10×D60.

4. The coefficient of uniformity (CV) is the ratio of _________
a) D60 and D10
b) D30 and D10
c) D10 and D30
d) D10 and D30

Explanation: The coefficient of uniformity CV, is defined as the ratio of D60 and D10
i.e.CV = D60/ D10.

5. The curve situated at the right side of the particle size distribution curve is _________
a) Coarse-grained soil
b) Fine-grained soil
c) coarse-grained soil
d) None of the mentioned

Explanation: The right side the particle size distribution curve shows the coarse-grained while the left shows the relatively fine-grained soil.

6. What is the time of settlement of coarse particle of a soil sample, of diameter 0.5?
Take γ=0.905D2 and height of water tank as 5 m.
a) 11.6 seconds
b) 72.8 seconds
c) 14 seconds
d) 22.1 seconds

Explanation: γ=0.905(0.5)2=0.2263 m/sec
Time of settlement, T=h/v =5/0.2263=22.1 seconds.

7. A curve with a flat portion, in particle size distribution curve represent __________
a) Intermediate size particle are missing
b) Intermediate size particles are present
c) Smaller size particle are present
d) Large size particles are present

Explanation: A curve with a flat portion represents oil in which intermediate size particle are missing.

8. The D10 represents a size, such that _________ of the particles are finer than this size.
a) 20%
b) 60%
c) 10%
d) 100%

Explanation: The D10 represents a size, in mm such that 10% of the particle is finer than D10 size.

9. The time of settlement of the finest particle of soil sample is 15hr20min49sec. calculate the height of the water tank. Take D=0.01 mm, γ=0.905D2.
a) 5 m
b) 7 m
c) 12 m
d) 4 m

Explanation: γ=0.905(0.01)
γ=9.05×10-5
t = 15hr 20min 49sec =55429 sec
t=h/v
55429=h/9.05×10-5
h=55429×9.05×10-5
h = 5.000034 m.

10. The shape of the particle size curve is represented by _________
a) Effective size
b) Effective diameter
c) Uniform coefficient
d) Co-efficient of curvature

Explanation: Coefficient of the curvature Cc represent the shape of the particle size curve given by CC = (D40)2/D10×D30.

11. A particle-size distribution curve gives us an idea about __________
a) Type of soil
b) Properties of soil
c) All of the mentioned
d) None of the mentioned

Explanation: A particle-size curve shows both type and gradation of the soil.

Sanfoundry Global Education & Learning Series – Geotechnical Engineering.

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