This set of Metal Casting Multiple Choice Questions & Answers (MCQs) focuses on “Grain Size and Shape”.
1. The size and shape of particles in the soil cannot reflect material composition and grain formation.
a) True
b) False
View Answer
Explanation: The size and shape of particles in the soil reflect the material composition and grain formation. And also include the escaping from a mineral matrix and depositional environments. The common processes involve the formation of small and large size grains in the soil mixture which is used for making mould.
2. The grain size distribution of soil basically determines inter-particle forces and its packing.
a) True
b) False
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Explanation: Soil is mainly made of grains which size distribution estimates the particle-level forces and the inter-particle packing. Hence, the grain size distribution plays a vital role in the soil systems. The shape of grain is classified at the three different parameters which are global form, surface features and surface roughness.
3. Quartz grains are generally fine or small in shape and size during analysis of quartz.
a) True
b) False
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Explanation: Quartz grains are generally coarse in size during analysis of quartz which is greatly affected by the solidification of quartz in the igneous rocks. The shape and surface characteristics reflect the mechanical and chemical effects after the releasing of grains. From chemical to mechanically controlling of shape, the transition part occurs between the particles of 50mm to 400mm size.
4. Large particles in soil increase the chances of imperfection and brittle failure.
a) True
b) False
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Explanation: The Large particles in soil increase the chances of imperfections and brittle failure. Reversely, smaller particles are strengthened by the decrease in imperfections. This makes the failure advantageous that occurs due to the presence of cleavage at the crystal planes. High cooperating conditions increases the breaking of extended particles and shear abrasion.
5. Which of the following equipment can be used for determining the grain size of soil particles?
a) Sprue
b) Gate
c) Runner
d) Sieve
View Answer
Explanation: Analysis of grain size of soils particles containing mostly large size particles is completed by using sieves. It is a device which normally consists of openings of same size and shape through which grains or particles of soil passes which should be smaller in size as compared to the size of openings, and the very large particles retained on the sieve.
6. Analysis of very small size grains of soil can also be possible by using sieves.
a) True
b) False
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Explanation: Analysis of very small size grains of soil cannot be possible by using sieves, because of very small size of sieve openings, it is very difficult to get pass the grains. Then for the analysis of small size grains, hydrometer analysis is done which is based on stoke’s law that states that the larger the grain size, the larger it’s settling speed in a fluid.
7. In a hydrometer test, a dispersing agent is mixed with water to increase its density.
a) True
b) False
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Explanation: For the analysis of small size grains of soil, a hydrometer test is performed in which a dispersing agent is used which blended with water to increase its specific gravity that indicates an increase in density of liquid. It also affects the variation of temperature of the liquid from the hydrometer calibration temperature.
8. It becomes easier to read the bottom part of the meniscus when the hydrometer is in a soil suspension.
a) True
b) False
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Explanation: It is impossible to read the bottom part of the meniscus when the hydrometer is in a soil suspension. In the hydrometer test, it is very necessary or essential to form a graph or table that gives a composite correction as a function of temperature for the present of dispersing agent in the hydrometer.
9. In a hydrometer test, soil used should be dispersed first in order to eliminate particle coagulation.
a) True
b) False
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Explanation: For the analysis of small size grains of soils in hydrometer test, soil sample used should be dispersed first in order to eliminate the particle coagulation. This is mainly accomplished by blending of soil with the solution of sodium hexametaphophate and then stirring is done to get a proper uniform solution.
10. The grain size distribution is mainly carried out to determine the strength and permeability of the soil.
a) True
b) False
View Answer
Explanation: The grain size distribution is fundamental for determining the properties of soil. It is mainly carried out for the classification of soil and to estimate the engineering properties like strength, permeability, compressibility and shear strength. Practically, the grain size distribution of soil is obtained by integrating the data gained from tests like mechanical sieving and hydrometer testing.
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