Free Soil Science MCQs with Answers

• A. MgCO3
• B. CaMg (CO3)2
• C. CaCO3
• D. None of the above

Explanation: Dolomite is a double carbonate mineral containing calcium and magnesium, so its formula is CaMg(CO3)2.

• A. > 50 mg kg-1
• B. > 10 mg-1
• C. > 400 mg kg-1
• D. None of these

Explanation: Plant zinc toxicity is commonly associated with tissue concentrations above about 400 mg kg⁻¹, although the precise threshold varies with…

• A. < 4 dsm-1
• B. Equal to 4 dsm-1
• C. 4-8 dsm-1
• D. None of the above

Explanation: A salt-free or nonsaline soil generally has saturated paste electrical conductivity below 4 dS m⁻¹.

• A. NH nitrogen the NO3 nitrogen in soil
• B. NO2 to NO3 nitrogen in soil
• C. NO3 nitrogen to NH4 + in soil
• D. None of the aboveFind Geological Maps

Explanation: Nitrification is the aerobic microbial oxidation of ammonium nitrogen, first to nitrite and then to nitrate.

• A. NH4OH
• B. NH4Cl
• C. NaOH
• D. None of the above

Explanation: Humic substances are commonly extracted from soil organic matter with alkaline sodium hydroxide, which dissolves humic and fulvic…

• A. Gapon
• B. Liekig
• C. Neir
• D. Felbeek

Explanation: Felbeek is credited in soil-organic-matter literature with defining or describing humic acid.

• A. Amino acid
• B. Lignin
• C. fats
• D. Cellulose

Explanation: Lignin has a complex aromatic structure and resists microbial breakdown, so it decays more slowly than amino acids, fats, and cellulose.

• A. Basidiomycetes
• B. Endospore
• C. Ascomycetes
• D. None of the aboveHire Grant Writers

Explanation: Ascomycetes are a very widespread fungal group, and many members live as saprophytes by decomposing dead organic matter.

• A. Protozoa
• B. Virus
• C. None of the aboveAccess Government Careers
• D. Both a & b

Explanation: In broad soil-microbiology usage, microbiota includes microscopic organisms such as protozoa and viruses along with bacteria and fungi.

• A. All the above
• B. Inceptisols
• C. Entisols
• D. Arid soils

Explanation: Arid soils, Inceptisols, and Entisols all occur widely in Pakistan because of its dry climate, young alluvial deposits, and weakly…

• A. Primary hydration
• B. Residence timeFind Geological Maps
• C. Normality
• D. ppm

Explanation: Residence time is the period an ion or water molecule remains within a particular soil or environmental compartment before leaving or…

• A. 40%
• B. 30%
• C. 58%
• D. 20%

Explanation: About 40% of the world's arable soils are commonly reported as acidic, mainly because of leaching in humid regions.

• A. Neutral soilsAccess Government Careers
• B. Saline-sodic soils
• C. Sodic soils
• D. Saline soils

Explanation: Saline soils have an EC above 4 dS m−1, ESP below 15, and usually pH below 8.5. Sodic soils instead have high ESP and commonly a higher pH.

• A. pH
• B. SAR
• C. EC
• D. ESR

Explanation: pH expresses hydrogen-ion activity and therefore indicates how acidic or basic a soil solution is.

• A. Table
• B. Both a & b
• C. Fume hoods
• D. None of the aboveSoil

Explanation: A fume hood removes hazardous vapours and protects the user while concentrated acids, bases, or volatile chemicals are handled.

• A. Ammonium sulphate Iron sulphate
• B. Sodium ammonium sulphate
• C. None of the above
• D. Ferrous Ammonium sulphate

Explanation: Ferrous ammonium sulfate, also called Mohr's salt, has the composition (NH4)2SO4·FeSO4·6H2O. The iron is in the ferrous, or Fe²⁺, state.

• A. Wilting point
• B. Field capacity
• C. Available water
• D. Hygroscopic water

Explanation: Wilting point is the lower limit of plant-available water, where soil retains water too tightly for roots to absorb it.

• A. Macro element
• B. Heavy metal
• C. Secondary element
• D. Free element

Explanation: Chromium is classified as a heavy metal and can become a soil and water pollutant at elevated concentrations.

• A. Sedimentation
• B. Nitrification
• C. Denitrification
• D. Eutrophication

Explanation: Eutrophication results from excess nutrients, especially nitrogen and phosphorus, stimulating algal growth; decomposition then consumes…

• A. Dispersion of soil particles
• B. Cementing of soil particles
• C. Agregation of soil particles
• D. All the aboveGeology

Explanation: Sodium hexametaphosphate is a dispersing agent used to separate individual soil particles during texture analysis.