Which of the following is not a raw-material for fertilizer industry?

Question

UnlockIAS · Accepted Answer

Correct — D, Caustic soda. Caustic soda (sodium hydroxide, NaOH) is a product of the chlor-alkali industry and is used in soap, paper, textiles, alumina and detergents — not as a feedstock for fertilizers. The other three are all genuine fertilizer raw materials: naphtha is a feedstock for making ammonia (and hence nitrogenous fertilizers like urea), sulphur is turned into sulphuric acid to make phosphatic fertilizers, and gypsum is used in producing ammonium sulphate and as a source of calcium and sulphur. So caustic soda is the odd one out.

Why the other options are wrong — (a) A petroleum fraction used as feedstock to produce ammonia — the building block of nitrogenous fertilizers such as urea; it IS a fertilizer raw material.  (b) Used in the manufacture of ammonium sulphate and as a soil amendment supplying calcium and sulphur; it IS a fertilizer raw material.  (c) Converted to sulphuric acid, which is essential for making phosphatic fertilizers (single superphosphate, DAP); it IS a fertilizer raw material.

Concept: The fertilizer industry draws on distinct raw materials for each nutrient: nitrogen from ammonia (made from natural gas or naphtha), phosphorus from rock phosphate treated with sulphuric acid (from sulphur), and potassium from potash. Gypsum and sulphur feed the phosphatic/ammonium-sulphate lines. Caustic soda belongs to a different family — the chlor-alkali industry — so it is not a fertilizer input.

State PCS 2020 Q62 — Economy PYQ with Answer

State PCS 2020 Q62 — Economy PYQ with Answer