Q.91
ICAR AIEEA PG 2024 - Physical Science
MCQ (Single Correct) +4 −1
English हिन्दी
The form of phosphorus in rock phosphate:
रॉक फॉस्फेट (rock phosphate) में फॉस्फोरस का रूप कौन सा होता है?
EXPLANATION Chemical Fertilizers: Manufacture, Composition, Chemistry and Transformations of N, P, K Fertilizers

Rock phosphate (phosphorite) is a natural sedimentary/igneous rock deposit mined as the primary raw material for phosphatic fertilizers:
The phosphorus in rock phosphate exists primarily as insoluble tricalcium phosphate [$\text{Ca}_3(\text{PO}_4)_2$] and apatite minerals [such as fluorapatite $3\text{Ca}_3(\text{PO}_4)_2\cdot\text{CaF}_2$ and hydroxyapatite $3\text{Ca}_3(\text{PO}_4)_2\cdot\text{Ca(OH)}_2$].
It is insoluble in water and only slightly soluble in citric acid, making it suitable for direct application only in strongly acidic soils ($pH \lt 5.5$).
Mono-calcium phosphate [$\text{Ca}(\text{H}_2\text{PO}_4)_2$] is the water-soluble form present in superphosphates.
Di-calcium phosphate [$\text{CaHPO}_4$] is citrate-soluble.
(Official Answer Key: Option 3: $\text{Ca}_3(\text{PO}_4)_2$).

रॉक फॉस्फेट (Rock phosphate) एक प्राकृतिक खनिज अयस्क है जो फॉस्फोरस उर्वरकों के निर्माण का प्राथमिक कच्चा माल है:
रॉक फॉस्फेट में फॉस्फोरस मुख्य रूप से अघुलनशील ट्राई-कैल्शियम फॉस्फेट [$\text{Ca}_3(\text{PO}_4)_2$] और एपेटाइट खनिजों (जैसे फ्लोरोएपेटाइट और हाइड्रॉक्सीएपेटाइट) के रूप में उपस्थित होता है।
यह जल में पूरी तरह अघुलनशील होता है, इसलिए इसका सीधा प्रयोग केवल अत्यधिक अम्लीय मृदाओं ($pH \lt 5.5$) में ही प्रभावी होता है।
मोनो-कैल्शियम फॉस्फेट [$\text{Ca}(\text{H}_2\text{PO}_4)_2$] सुपरफॉस्फेट में पाया जाने वाला जल-घुलनशील रूप है।
डाई-कैल्शियम फॉस्फेट [$\text{CaHPO}_4$] साइट्रेट-घुलनशील रूप है।
(NTA आधिकारिक उत्तर कुंजी: विकल्प 3: $\text{Ca}_3(\text{PO}_4)_2$)।

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