Soil Science - Study Mode

[#821] Major source of water used by the plants is
Correct Answer

(A) Hygroscopic water

[#822] Boron is injurious to plant when irrigational water contains . . . . . . . . concentration of boron.
Correct Answer

(D) > 3 ppm

Explanation

Solution: Boron is injurious to plants when irrigation water contains more than 3 ppm concentration of boron. When the concentration of boron in irrigation water is above the maximum level it causes havoc on the yield of the crop. There is various plant crop sensitive to boron. although boron is an essential nutrient for the plants it is required in small amounts. Boron toxicity can cause conspicuous necrotic lesions in the interveinal areas of older leaves, leading to premature senescence and shredding of the leaves.

[#823] Which type of chemical bond is seen in HCl?
Correct Answer

(C) Covalent

Explanation

Solution: A polar covalent bond is seen in HCl between hydrogen and chlorine. Hydrogen chloride (HCl) is a diatomic molecule, consisting of a hydrogen atom H and a chlorine atom Cl connected by a covalent bond. It is formed by the sharing of an electron pair between the two atoms. The chlorine atom is much more electronegative than the hydrogen atom, which makes this bond polar.

[#824] Match the following columns Column I (Bacteria) Column II (Function) a. Nitrobacteria 1. Fixation of atmospheric nitrogen b. Ammonifying bacteria 2. Formation of NH 4 + nitrogen c. Denitrifying bacteria 3. Formation of NO 3 - nitrogen d. Rhizobium sp. 4. Formation of NO 2 nitrogen
Correct Answer

(C) a-3, b-2, c-4, d-1

Explanation

Solution: Nitrobacteria are obligate aerobes. It plays an important role in the nitrogen cycle by oxidizing nitrite (NO 3 - ) into nitrate and ultimately nitrogen in the soil. Ammonifying bacteria convert ammonia into atmospheric nitrogen. Denitrifying bacteria results in the conversion of nitrates in the soil to free atmospheric nitrogen. Rhizobium species are a group of bacteria that helps in fixing atmospheric nitrogen in plants.

[#825] Which type of structure is dominant in grasslands
Correct Answer

(A) Spheroidal

Explanation

Solution: Grasslands are areas where the vegetation is dominated by grasses. The spheroidal structure is dominant in grasslands, these have granular soil structure. The aggregates are 1 - 10 mm in diameter with rounded corners. This structure is usually seen in the A horizon or the layer of fine or medium-textured soils.