Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE MainChemistryPractical Chemistry

During Lassaigne's test for the detection of sulphur in an organic compound, the sodium fusion extract is treated with sodium nitroprusside. The appearance of a deep purple colour confirms the presence of sulphur. The correct chemical formula of the purple coloured complex formed is :

Options

  1. ANa ₂ [ Fe ( CN )₅ NOS ]
  2. BNa ₃ [ Fe ( CN )₅ NOS ]
  3. CNa ₄ [ Fe ( CN )₅ NOS ]
  4. DNa ₄ [ Fe ( CN )₆ ]

Correct answer

C. Na ₄ [ Fe ( CN )₅ NOS ]

Step-by-step solution

During Lassaigne's test for sulphur, the sodium fusion extract contains sodium sulphide ( Na ₂ S ). When sodium nitroprusside, Na ₂ [ Fe ( CN )₅ NO ] , is added to this extract, it reacts with the sulphide ions to form a deep purple coloured complex. The chemical reaction is given by: Na ₂ S + Na ₂ [ Fe ( CN )₅ NO ] Na ₄ [ Fe ( CN )₅ NOS ] Thus, the correct formula of the purple complex is Na ₄ [ Fe ( CN )₅ NOS ] . Answer: Na ₄ [ Fe ( CN )₅ NOS ]

Practice Practical Chemistry on Quantrex Academy →

More from Practical Chemistry

Passage: Consider the following reaction sequence in which J , K , L and M are the major products. Given: Atomic mass (in amu): H : 1 , C : 12 , N : 14 , O : 16 , S : 32 , Br : 80 2026Among Fe³⁺ , Pb²⁺ , Cu²⁺ and Mn²⁺ , identify the one that gets precipitated out while passing H₂S in presence of NH₄OH as group reagent. The highest possible oxidation state of the 2026Among Fe²⁺, Fe³⁺, Cr²⁺ and Zn²⁺ , the ion that shows positive borax bead test and with highest ionisation enthalpy is: 2026A salt with few drops of conc. HCl gives apple green colour in flame test. The group precipitate of the salt is dissolved in acetic acid and treated with K₂CrO₄ to give yellow prec 2026A student has been given 0.314 g of an organic compound and asked to estimate Sulphur. During the experiment, the student has obtained 0.4813 g of barium sulphate. The percentage o 2026In the Group analysis of cations, Ba ²⁺ ~ &~ Ca ²⁺ are precipitated respectively as 2026Consider three metal chlorides x , y and z, where x is water soluble at room temperature, y is sparingly soluble in water at room temperature and z is soluble in hot water. x , y a 2026By usual analysis, 1.00 g of compound ( X ) gave 1.79 g of magnesium pyrophosphate. The percentage of phosphorus in compound (X) is : (nearest integer) (Given, molar mass in g mol 2026 Full Practical Chemistry list All JEE Main PYQs