Part 1 - Objective questions (20 questions each worth 2 points) A mole of Na+ ha
ID: 39231 • Letter: P
Question
Part 1 - Objective questions (20 questions each worth 2 points) A mole of Na+ has (a) one centipoise of charge. (b) one decisiemens of charge. (c) one rem of charge. (d) one equivalence of charge. In acidic soils, adding ag lime normally increases nutrient availability and reduces heavy metal toxicities via (a) lowering pH. (b) increasing pH. (c) increasing H+ solubility. (d) lowering Eh. Plants uptake nitrogen as either (a) nitrite or ammonium. (b) nitrate and ammonium. (c) nitrite and ammonia. (d) nitrate and ammonia. The form of nitrogen that normally leaches out of the soil is (a) nitrite (b) nitrate. (c) ammonia. (d) ammonium. A general challenge of nitrogen in soil s its (a) high solubility. (c) low solubility. (c) high valence. (d) amphoteric nature. Ammonium fixation refers to (a) the NH4? molecule getting trapped into the vermiculite interlayer and creating illite. (b) symbiotic bacteria converting N2-gas into NH4+. (c) symbiotic bacteria converting N2-gas into NO3-. (d) the Haber-Bosch industrial conversion of N2 into plant available forms of nitrogen. Phosphorus generally accounts for about % of a plant?s dry weight. Environmental loss of phosphorus from soil is generally via (a) leaching of orthophosphate. (b) leaching of elemental phosphorus. (c) volatilization. (d) erosion. Labile P refers to phosphorus that isExplanation / Answer
1. A sodium (Na) atom loses one electron becomes a sodium ion (Na+), with a charge of +1. Thus, 1 mole of Na+ has one equivalance of charge. option d is correct.
2. Addition of ag lime to acidic soils increases the pH of the soils so that the nutrients are available to plants. Option b is correct.
3. Plants directly cannot take up nitrogen. They take up nitrogen as nitrates and ammonia. Option d is correct.
4. Nitrate is the form of nitrogen that is available to plants in the soil. Normally, the nitrate is leached away from the soils. Option b is correct.
5. Nitrogen in soil is not much soluble and hence plants uptake nitrogen in the form of nitrates. Option b is correct.
6. Ammonium fixation means symbiotic fixation of atmospheric nitrogen by bacteria that convert nitrogen to nitrates and nitrates are further reduced to ammonia. Option c is correct.
7. Phosporous generally accounts for 30% of dry weight.
8. Environmental phosphorous loss is mainly due to soil erosion. Option d is correct.
9. Labile phosphorous refers to phosphorous not available to plants.