Soil Science - Study Mode
[#761] Chemical (Grigg & Tamn reagent) used for extraction of Mo is
Correct Answer
(D) Ammonium oxalate, pH 3.3
Explanation
Solution: The Chemical (Grigg & Tamn reagent) used for extraction of Molybdenum is Ammonium acetate at pH 3.3 . The Grigg or Tamn reagent (acid ammonium oxalate) is considered to be the best for the determination of available molybdenum. The reagent produces oxalate ions which replace the molybdate on soil colloids and clay. This exchange of oxalate and molybdate ions becomes irreversible by the formation of Mo-oxalic acid complexes.
[#762] In Minimum thermometer, material used is
Correct Answer
(A) Alcohol
Explanation
Solution: In the minimum thermometer, the material used is Alcohol . The minimum thermometer is one that automatically registers the lowest temperature attained during an interval of time. The alcohol in the glass minimum thermometer contains a dumbbell-shaped index that is kept on the bulb side of the meniscus by surface tension. The thermometer is installed in a horizontal mounting so that as the temperature falls, the index is pulled toward the bulb and remains at the minimum point as the temperature rises.
[#763] Gypsum block can measure water potential up to
Correct Answer
(A) 1 - 15 bar
Explanation
Solution: Gypsum block can measure water potential up to 1 - 15 bar. A soil moisture block often referred to as gypsum block is a device for measuring soil moisture changes. The amount of water in the soil is determined by the electrical resistance between the two electrodes within the gypsum block. More water present in the soil will reduce the resistance, while less water will increase it.
[#764] The mineral chlorite has an extra layer of
Correct Answer
(B) Illite
Explanation
Solution: The mineral chlorite has an extra layer of Illite. The illite is abundant throughout the illite-chlorite predominant zone. Layers of illite and chlorite are semicoherent. The chlorites are a group of phyllosilicate minerals common in low-grade metamorphic rocks and altered igneous rocks.
[#765] Among the following, soil of which stage is most mature?
Correct Answer
(A) Senile
Explanation
Solution: Mohr and van Baren have recognized the five stages of soil development that are Initial Stage, Juvenile stage, Virile, Senile and final. The senile stage of soil is most matured as in this stage, Decomposition arrives at a final stage and only the most resistant minerals have survived.