Ncert Solutions Chemistry Class 11th

12.50. A nucleophile 

(a) Brings an electron pair to thereactive site

(b) Takes away anelectron pair from reactive site

(c) Brings nucleus of one atom near the nucleus of another atom

(d) Brings electrons of one atom near the electrons of another atom

12.49. Which elements are estimated by Liebig’s Method?

(a) Oxygen and nitrogen (b) Carbon and hydrogen (c) Sulphur and Phosphorus (d) Calcium and potassium

12.3. Nitrogen is estimated by

(a) Carius method (b) Dumas method(c) Kjeldahl’s method (d) both b and c

12.47. The common techniques used for purification are as follows:

(a) Sublimation

(b) Crystallisation

(c) Distillation

(d) all of the above

MCQs

 12.46 Hyperconjugation is a

(a) permanent effect (b) temporary effect (c) dual effect (d) none

12.5. Assertion: Electromeric effect is a permanent effect.

Reason: Organic compounds having a multiple bond show this effect in the presence of an attacking reagent.

12.44. Assertion: The energy of actual structure of the molecule(the resonance hybrid) is lower than that of anyof the canonical structures.

Reason: Resonance is particularly important when the contributing structures are equivalent in energy.

12.43.Assertion: In homolytic cleavage, the movement of a single electron takes place instead of an electron pair.

Reason: A homolytic cleavage yields carbocations or carbanions.

12.40. The reaction:
CH₃CH₂I + KOH (aq) → CH₃CH₂OH + KI is classified as:
(a) electrophilic substitution (b) nucleophilic substitution
(c) elimination (d) addition

12.39. The best and latest technique for isolation, purification and separation of organic compounds is:

 (a) Crystallisation (b) Distillation(c) Sublimation (d) Chromatography