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Class XI · Chemistry

Purification and Characterisation of Organic Compounds: NEET MCQ practice

97 practice questions on Purification and Characterisation of Organic Compounds, each with an explanation. Practise them chapter by chapter in the GyaanLoop app.

97

Practice questions

65

Easy

30

Medium

2

Hard

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What Purification and Characterisation of Organic Compounds covers

Topics in the NEET (UG) 2026–27 syllabus for this chapter.

  • Purification- crystallization, sublimation, distillation, differential extraction, chromatography
  • Qualitative analysis- detection of nitrogen, sulphur, phosphorus and halogens
  • Quantitative analysis (basic principles)- estimation of carbon, hydrogen, nitrogen, halogens, sulphur, phosphorus
  • Calculations of empirical and molecular formulae, numerical problems in organic quantitative analysis

Sample questions on Purification and Characterisation of Organic Compounds

Try each one, then open the answer and explanation.

Question 1 · Practice question

Solid iodine is an example of

  1. A.covalent solid
  2. B.ionic solid
  3. C.molecular solid
  4. D.metallic solid
Show answer

Answer: C. molecular solid

Solid iodine consists of I₂ molecules held together by weak van der Waals forces, which is the definition of a molecular solid. It is not a covalent network solid because the covalent bonds are only within each molecule, not extending throughout the entire solid.

Question 2 · Practice question

An inorganic compound producing an organic compound on heating is

  1. A.ammonium cyanate
  2. B.soda lime
  3. C.sodamide
  4. D.potassium cyanide
Show answer

Answer: A. ammonium cyanate

Ammonium cyanate (NH₄OCN) on heating undergoes rearrangement to form urea (NH₂CONH₂), which is an organic compound, known as Wöhler's synthesis. Soda lime and sodamide do not yield organic compounds directly on heating alone, while potassium cyanide remains inorganic. This is a recall-based question linking inorganic-organic transformation.

Question 3 · Practice question

74 gm of sample on complete combustion gives 132 gm CO₂ and 54 gm of H₂O. The molecular formula of the compound may be

  1. A.C₅H₁₂
  2. B.C₄H₁₀O
  3. C.C₃H₆O₂
  4. D.C₃H₇O₂
Show answer

Answer: C. C₃H₆O₂

First, calculate moles of CO₂ and H₂O to find moles of C and H in the sample. Subtract their total mass from 74 g to find mass of oxygen, then moles of oxygen. This gives empirical formula C₃H₆O₂, which matches option (c) and also its molar mass equals 74 g/mol. Option (b) C₄H₁₀O has wrong H/C ratio, and (d) C₃H₇O₂ has extra H atoms; both would give different combustion results.

Question 4 · Practice question

0.92 g of an organic compound was analysed by combustion method. The mass of the U-tube increased by 1.08 g. What is the percentage of hydrogen in the compound?

  1. A.13.04%
  2. B.52.17%
  3. C.65.21%
  4. D.11.30%
Show answer

Answer: A. 13.04%

In combustion analysis, increase in U‑tube mass = mass of water formed. Mass of hydrogen in water = (2/18) × mass of water = (1/9) × 1.08 = 0.12 g. Percentage hydrogen = (0.12/0.92) × 100 = 13.04%. Option (d) 11.30% arises if you mistakenly use atomic weight of H as 1 but forget there are 2 H atoms in H₂O, or miscalculate 1.08/0.92 wrongly.

Question 5 · Practice question

An organic compound gave 0.4655 g of CO₂ on complete combustion. If the mass of the compound taken was 0.2115 g, what is the percentage of C in it?

  1. A.13.30%
  2. B.26.67%
  3. C.60.03%
  4. D.28.80%
Show answer

Answer: C. 60.03%

All carbon in the compound ends up in CO₂. The mass of carbon in the CO₂ produced is (12/44) × mass of CO₂. Dividing that by the mass of the compound and multiplying by 100 gives the percentage of carbon. Option (a) and (b) correspond to incorrect fractions of the CO₂ mass, while (d) is close to the percentage of C in CO₂ (27.3%) but not applicable here.

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