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Practice each question, then open the answer or worked solution.
Why does SO3 act as an electrophile?
Oxygen is more electronegative than sulphur and the electron density at S in SO3 is reduced and they need more electrons to suppress the partial positive charge and hence they act as an electrophile.
Resonance structures of propenal are given below. Which of these resonating structures is more stable? Give a reason for your answer.
The structure I will be more stable than structure II because all the atoms have a complete octet in structure I, and the carbon atom having a positive charge don’t have a complete octet in structure II.
By mistake, an alcohol (boiling point 97°C) was mixed with a hydrocarbon (boiling point 68°C). Suggest a suitable method to separate the two compounds. Explain the reason for your choice.
We can separate the mixture by steam distillation. Both alcohol and hydrocarbon don’t have much difference in the boiling point. Steam distillation is particularly used for the purification of temperature-sensitive material.
Which of the two structures (A) and (B) given below is more stabilised by resonance? Explain.
(A) CH3COOH (B) CH3COO-
The two resonating structures in compound A are not equivalent, whereas compound B, having a negative charge on the oxygen atom, has the two equivalent structures; hence compound B is more stable.
IV. Matching Type
In the following questions, more than one correlation is possible between
options of Column I and Column II. Make as many correlations as you can.
Match the type of mixture of compounds in Column I with the technique of
separation/purification given in Column II.
| Column I
(i) Two solids which have different solubilities in a solvent and which do not undergo a reaction when dissolved in it. (ii) The liquid that decomposes at its boiling point (iii) Steam volatile liquid (iv) Two liquids which have boiling points close to each other (v) Two liquids with the large difference in boiling points. |
Column II
(a) Steam distillation (b) Fractional distillation (c) Simple distillation (d) Distillation under reduced pressure (e) Crystallisation |
(i) is e
(ii) is d
(iii) is a
(iv) is b
(v) is c
Match the terms mentioned in Column I with the terms in Column II.
| Column I
(i) Carbocation (ii) Nucleophile (iii) Hyperconjugation (iv) Isomers (v) sp hybridisation (vi) Electrophile |
Column II
(a) Cyclohexane and 1- hexene (b) Conjugation of electrons of C–Hσ bond with empty p-orbital present at adjacent positively charged carbon. (c) sp2 hybridised carbon with empty p-orbital (d) Ethyne (e) Species that can receive a pair of electrons (f) Species that can supply a pair of electrons. |
(i) is c
(ii) is f
(iii) is b
(iv) is a
(v) is d
(vi) is e
Match Column I with Column II.
| Column I
(i) Dumas method (ii) Kjeldahl’s method (iii) Carius method (iv) Chromatography |
Column II
(a) AgNO3 (b) Silica gel (c) Nitrogen gas (d) Free radicals (e) Ammonium sulphate |
(i) is c
(ii) is e
(iii) is a
(iv) is b
(v) is d
Match the intermediates given in Column I with their probable structure in
Column II.
| Column I
(i) Free radical (ii) Carbocation (iii) Carbanion |
Column II
(a) Trigonal planar (b) Pyramidal (c) Linear |
(i) is a
(ii) is a
(iii) is b
Match the ions given in Column I with their nature given in Column II.
(i) is a, b and d
(ii) is b
(iii) is b
(iv) are c and d