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Unit 3 - Practice Quiz

SOL103

1 According to the ISSS (International Society of Soil Science) classification system, what is the particle size diameter range for silt?

A. 2.00 – 0.20 mm
B. 0.20 – 0.02 mm
C. 0.02 – 0.002 mm
D. < 0.002 mm

2 Which law governs the settling velocity of soil particles in a liquid suspension, forming the basis of sedimentation analysis?

A. Darcy's Law
B. Stokes' Law
C. Fick's Law
D. Beer's Law

3 Which soil physical property is considered a basic property that cannot be easily altered by tillage or management practices?

A. Soil Structure
B. Bulk Density
C. Soil Texture
D. Porosity

4 What is the typical value assumed for the Particle Density (PD) of a normal mineral soil when actual data is unavailable?

A.
B.
C.
D.

5 Calculate the Total Porosity (%) of a soil if the Bulk Density is and the Particle Density is .

A. 40%
B. 45%
C. 50%
D. 60%

6 Which type of soil structure is typically found in the A-horizon of grassland soils and is considered best for agriculture?

A. Platy
B. Prismatic
C. Columnar
D. Granular (Spheroidal)

7 What is the relationship between Bulk Density (BD) and Total Porosity?

A. As BD increases, Porosity increases
B. As BD increases, Porosity decreases
C. BD and Porosity are unrelated
D. BD is always equal to Porosity

8 In the Munsell soil color chart notation 10YR 5/6, what does the number 5 represent?

A. Hue
B. Value
C. Chroma
D. Spectral color

9 Which soil consistency term describes the range of water content where the soil exhibits plastic properties?

A. Plasticity Index
B. Liquid Limit
C. Flocculation point
D. Shrinkage Limit

10 The specific heat of soil solids is approximately what fraction of the specific heat of water?

A. 1/5 (0.2)
B. 1/2 (0.5)
C. Equal (1.0)
D. Twice (2.0)

11 Under normal conditions, how does the concentration of Carbon Dioxide () in soil air compare to atmospheric air?

A. Lower in soil air
B. About the same
C. Higher in soil air
D. Absent in soil air

12 Which force is primarily responsible for the retention of water against gravity in micropores?

A. Gravitational force
B. Centrifugal force
C. Capillarity (Adhesion and Cohesion)
D. Osmotic pressure

13 What is the pF value corresponding to the Field Capacity of a typical medium-textured soil?

A.
B. 2.53
C. 4.18
D. 7.0

14 The Permanent Wilting Point (PWP) is conventionally defined at a soil water potential of:

A. -0.33 bar
B. -15 bars
C. -31 bars
D. -60 bars

15 Which instrument is most suitable for measuring soil water tension in the wet range ($0$ to bar)?

A. Neutron Probe
B. Tensiometer
C. Pressure Plate Apparatus
D. Electrical Resistance Block

16 The movement of heat through the soil profile is primarily governed by which law?

A. Fick's Law
B. Fourier's Law
C. Darcy's Law
D. Stefan-Boltzmann Law

17 Which of the following creates Platy structure in soils?

A. High organic matter content
B. Compaction by heavy machinery
C. Alternate wetting and drying
D. Root penetration

18 If a soil sample has a moist weight of 150g, a dry weight of 120g, and a volume of 100 , what is its Bulk Density?

A.
B.
C.
D.

19 The difference between water retained at Field Capacity and the Permanent Wilting Point is known as:

A. Gravitational Water
B. Hygroscopic Water
C. Available Water Capacity
D. Unavailable Water

20 Oxygen Diffusion Rate (ODR) becomes critical for root growth when it falls below:

A.
B.
C.
D.

21 Which textural class has the highest specific surface area?

A. Sandy loam
B. Silt loam
C. Clay
D. Loamy sand

22 The Hygroscopic Coefficient roughly corresponds to a soil water potential of:

A. -15 bars
B. -31 bars
C. -100 bars
D. -1000 bars

23 Which gas exchange mechanism is the most dominant in soil aeration?

A. Mass Flow
B. Diffusion
C. Dissolution in water
D. Barometric pumping

24 Soil Albedo refers to:

A. The heat capacity of the soil
B. The fraction of incident solar radiation reflected by the soil surface
C. The thermal conductivity of the soil
D. The emission of long-wave radiation

25 What is the effect of adding organic matter on Soil Bulk Density?

A. It increases Bulk Density
B. It decreases Bulk Density
C. It has no effect
D. It increases Particle Density but not Bulk Density

26 Which Atterberg limit represents the water content at which soil changes from a semi-solid to a plastic state?

A. Liquid Limit (LL)
B. Plastic Limit (PL)
C. Shrinkage Limit (SL)
D. Sticky Point

27 In the capillary rise equation , what does represent?

A. Radius of the capillary pore
B. Radius of the soil particle
C. Resistance to flow
D. Rainfall intensity

28 Total soil water potential () is the sum of several components. Which component is always negative in unsaturated soils?

A. Gravitational potential ()
B. Matric potential ()
C. Pressure potential ()
D. Hydraulic head

29 The phenomenon where the relationship between soil water content and water potential depends on whether the soil is drying (desorption) or wetting (sorption) is called:

A. Capillarity
B. Percolation
C. Hysteresis
D. Hydraulic Conductivity

30 Which of the following soils warms up the slowest in the spring?

A. Dry sandy soil
B. Wet clay soil
C. Dry loam soil
D. Dark colored dry soil

31 A soil aggregate formed by natural processes is called a ped, whereas an artificial lump formed by tillage is called a:

A. Clod
B. Pan
C. Prism
D. Concretion

32 Which form of water is held between the tension of -31 bars and roughly -10,000 bars?

A. Capillary water
B. Gravitational water
C. Hygroscopic water
D. Available water

33 Darcy's Law () describes the flow of water in saturated soil. What does K represent?

A. Kinetic energy
B. Hydraulic gradient
C. Hydraulic conductivity
D. Porosity factor

34 What is the mathematical definition of Particle Density?

A.
B.
C.
D.

35 Which structure type usually characterizes the B horizon (subsoil)?

A. Granular
B. Crumb
C. Blocky or Prismatic
D. Single Grained

36 The Textural Triangle utilizes the percentages of which fractions to determine soil class?

A. Sand and Silt only
B. Sand, Silt, and Organic Matter
C. Sand, Silt, and Clay
D. Clay and Gravel

37 Thermal conductivity () is generally highest in:

A. Soil Air
B. Soil Water
C. Soil Solids (Quartz)
D. Soil Organic Matter

38 Which instrument uses radioactive scattering to measure soil moisture content?

A. Tensiometer
B. Neutron Probe
C. Gypsum Block
D. Thermocouple psychrometer

39 The ratio of the volume of voids (pores) to the volume of solids is known as:

A. Porosity ()
B. Void Ratio ()
C. Bulk Density
D. Air Capacity

40 A soil with a bulk density of is likely to have:

A. High porosity and easy root penetration
B. Low porosity and restricted root growth
C. High organic matter content
D. Granular structure

41 Gravitational water moves through the soil primarily through:

A. Micropores
B. Macropores
C. Hygroscopic films
D. Vapor phase

42 Which of the following contributes to high Soil Consistency (resistance to rupture) in dry soils?

A. High sand content
B. High clay content
C. High water content
D. Low bulk density

43 In the context of soil air, aeration porosity refers to:

A. Total porosity
B. Volume of pores filled with water
C. Volume of pores filled with air at Field Capacity
D. Micropore space

44 If the Plasticity Index (PI) of a soil is 0, the soil is:

A. Highly plastic (Clay)
B. Non-plastic (Sand)
C. Moderately plastic (Loam)
D. Liquid

45 The upward movement of water from a water table towards the root zone occurs via:

A. Infiltration
B. Percolation
C. Capillary rise
D. Surface runoff

46 Infiltration refers to:

A. Downward movement of water through the soil profile
B. Entry of water into the soil across the surface
C. Loss of water vapor from the surface
D. Lateral movement of water

47 Which soil temperature regime is optimal for the nitrification process by bacteria?

A. 0 - 5 °C
B. 10 - 15 °C
C. 25 - 35 °C
D. 45 - 55 °C

48 Massive and Single-grained are termed as:

A. Structureless conditions
B. Ideal agricultural structures
C. Types of peds
D. Aggregated soils

49 The Heat Capacity of a soil is defined as:

A. The amount of heat required to raise the temperature of a unit mass/volume by 1°C
B. The rate at which heat flows through the soil
C. The maximum temperature a soil can reach
D. The ability of soil to reflect heat

50 A pycnometer is a laboratory device typically used to determine:

A. Bulk Density
B. Particle Density
C. Soil Strength
D. Hydraulic Conductivity