All of the following are nitrogen fertilisers EXCEPT
Answer: C
Single superphosphate supplies phosphate and no nitrogen at all. The other three are all nitrogen carriers differing mainly in their concentration and their behaviour in the soil. Its own nutrients are phosphate and calcium.
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State whether the following is true or false.
Ammonium nitrate is subject to storage and transport restrictions.
Answer: D
It is an oxidiser that can detonate under the right conditions of confinement and contamination, and several major industrial disasters involved it. Calcium ammonium nitrate was developed as a safer diluted alternative.
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The wet process for phosphoric acid treats phosphate rock with
Answer: A
Calcium sulphate is filtered off as phosphogypsum, and its disposal in large quantity is the main environmental problem of the route. The acid produced is impure but adequate for fertiliser use. Its filtration is the heart of the plant.
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Assertion (A): Wet process phosphoric acid is not pure enough for food or detergent use.
Reason (R): It carries fluoride, iron, aluminium and other impurities from the phosphate rock.
Answer: B
Both are true and the reason gives the cause: the furnace process or a solvent purification step is used where a technical or food grade acid is needed. Fluoride is often recovered as a by-product. Purified acid commands a considerably higher price.
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Phosphogypsum is a by-product of
Answer: C
About five tonnes accompany each tonne of phosphorus pentoxide produced, and it usually carries a trace of radium from the rock. Stacking it is the common disposal route and a continuing liability. Its volume dwarfs that of the acid produced.
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Superphosphate is made by treating rock with sulphuric acid. If the rock is 30 per cent phosphorus pentoxide and the product is 16 per cent, how much product comes from one tonne of rock, ignoring losses?
Answer: D
The phosphorus pentoxide is conserved, so three hundred kilograms at sixteen per cent implies about one point nine tonnes of product. The added acid and water account for the increase in mass. Tracking the pentoxide is the whole calculation.
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Triple superphosphate differs from single superphosphate in being made with
Answer: A
Correct answer: phosphoric rather than sulphuric acid
Single superphosphate is rock treated with sulphuric acid, and the calcium sulphate formed dilutes the product to about 16 to 20 per cent available phosphate. Triple superphosphate uses phosphoric acid instead, so no sulphate is produced and the grade rises to around 46 per cent - which cuts the mass to be bagged, shipped and spread for the same nutrient.
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Consider the following statements about single and triple superphosphate.
1. Single superphosphate contains gypsum and so supplies sulphur too.
2. Triple superphosphate is roughly three times as concentrated.
3. Both are made by treating rock with sulphuric acid.
Answer: B
The first two are correct, and the sulphur in single superphosphate is a genuine agronomic benefit. The third is wrong because triple superphosphate uses phosphoric acid. The gypsum accounts for most of the difference.
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Diammonium phosphate is made by reacting
Answer: C
The reaction is strongly exothermic and the product supplies both nitrogen and phosphate, typically at eighteen and forty-six per cent. Monoammonium phosphate is made the same way with less ammonia. Both are widely traded as compound fertilisers.
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Three of the following supply phosphate. Which is the odd one out?
Answer: D
Correct answer: ammonium sulphate fertiliser
Ammonium sulphate supplies nitrogen and sulphur and no phosphate at all. The other three are the principal phosphate carriers: single and triple superphosphate from acidulated rock, and diammonium phosphate, which supplies both phosphate and nitrogen and is the most traded phosphate fertiliser.
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