Oxygen and Silicon combined make up roughly ______ % of the earth's crust?
Show answer Hide answer
Answer: C. 75 %
Explanation
Oxygen and silicon are the most abundant chemical elements in the lithosphere. Combined, these two vital elements constitute roughly 75 percent of the crust. Silicate minerals dominate the geological composition of most rocks on Earth. The Earth's crust is built primarily of a framework of silicate mineral structures. Oxygen makes up nearly half of the total crustal mass by weight. Silicon forms the central tetrahedra building block linked with oxygen atoms everywhere.
Geologists study crustal abundance to understand planetary formation and mineral resource distribution. Weathering of silicon-rich rocks provides the parent material for global pedogenesis processes. Quartz and feldspar represent the most common silicate minerals found in soils. Option A underestimates the combined abundance percentage of these two major crustal elements. Option B slightly overestimates the total percentage compared to standard geological consensus values. Option D suggests a lower total proportion than actual geochemical crustal measurements indicate.
- Subject
- Agriculture
- Category
- Agriculture
- Topic
- —
- Difficulty
- medium
Related questions
Q1. Organic Soils are categorized as ____________ and are additionally referred to as ____________ soils:
Show answer Hide answer
Answer: B. Histosols, peat & muck
Soils dominated by organic matter rather than mineral particles have unique classifications. Soil taxonomy officially categorizes these organic soils under the order Histosols. Common field terms for these organic deposi...
Q2. Humus generally denotes decomposed organic debris that has undergone multiple degradation and synthesis cycles. Humic substances comprise high-molecular-weight, highly acidic compounds ranging in color from yellow to black __________________, which can be isolated via various extraction protocols:
Show answer Hide answer
Answer: C. both A & B
Humus comprises complex degraded organic compounds formed through continuous biological synthesis cycles. Chemical extraction protocols separate these humic substances into specific distinct major fractions. Humic acid a...
Q3. Micas exhibit isomorphous substitution:____________?
Show answer Hide answer
Answer: B. Predominantly in octahedral layer
Mica sheet silicates feature layer structures with specific ionic substitution patterns. Isomorphous substitution in micas occurs predominantly within the internal octahedral layer. This structural substitution creates t...
Q4. Nitrosomonas and nitrobacter are collectively designated as_____________?
Show answer Hide answer
Answer: B. Nitrification
Nitrosomonas and Nitrobacter are specific genera of bacteria responsible for the two-step biological oxidation process known as nitrification.
Q5. By what chemical form do plants absorb phosphorus?
Show answer Hide answer
Answer: C. Both
Plants absorb essential phosphorus exclusively as dissolved inorganic orthophosphate ions from soil. The two primary ionic forms absorbed are dihydrogen phosphate and secondary hydrogen phosphate. Soil pH strictly determ...
Q6. In cotton plants, zinc deficiency is identified as_________?
Show answer Hide answer
Answer: C. Little leaf
Micronutrient deficiencies produce distinct visual symptoms in agricultural crops. Zinc deficiency in cotton plants is classically identified as little leaf syndrome. Stunted growth and drastically reduced leaf sizes cha...