Chemistry

Organic Chemistry

Question:

Identify the reagents shown in bold in the following equations as nucleophiles or electrophiles
(a) CH3COOH + HO ———–> CH3COO + H2O
(b) CH3COCH3 + CN ———–> (CH3)2 C(CN)(OH)
(c) C6H5 + CH3CO ———–> C6H5COCH3

Answer:

Nucleophiles: (a) and (b) and Electrophile : (c)

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Organic Chemistry

Q 1.

Classify the following reactions in one of the reaction type studied in this unit.
(a) CH3CH2Br + HS ———–> CH3CH2SH + Br
(b) (CH3)2C=CH2 + HCl ———–> (CH3)2CCl—CH3
(c) CH3CH2Br + HO ———–> CH2=CH2 + H2O + Br
(d) (CH3)3C—CH2OH + HBr ———–> (CH3)2 C Br CH2CH2CH3 + H2O

Q 2.

What are electrophiles and nucleophiles? Explain with examples:

Q 3.

Which elements are estimated by Liebig’s Method?

Q 4.

Complete the following:(CH3COO)2 Pb + Na2S ———->      

Q 5.

Electronegativity of carbon atoms depends upon their state of hybridization. In which of the following compounds, the carbon marked with asterisk is most electronegative?
ncert-exemplar-problems-class-11-chemistry-chapter-12-organic-chemistry-some-basic-principles-6

 

Q 6.

ncert-exemplar-problems-class-11-chemistry-chapter-12-organic-chemistry-some-basic-principles-8

(a) 2-Ethyl-3-methylpentane
(b) 3,4-Dimethylhexane
(c) 2-sec-Butylbutane
(d) 2,3-Dimethylbutane

Q 7.

In Carius method, sulphur is estimated by precipitating it as which compound?

Q 8.

What are electrophiles? Explain electrophile substitution reaction with the help of example.

Q 9.

Describe the method, which can be used to separate two compounds with different solubilities in a solvent S.

Q 10.

Two or more compounds having same the molecular formula but different functional groups are called functional isomers. Which of die following pairs are not functional group isomers?
(a) II and III (b) II and IV
(c) I and IV (d) I and II

Q 11.

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.

Q 12.

In the Lassaigne’s test for ntrogen in an organic compound, the Prussian blue colour is obtaine d due to the formation of:
(a) Na4[Fe(CN)6] (b)Fe4[Fe(CN)6]3
(c) Fe2[Fe(CN)6] (d)Fe3[Fe(CN)6]4 .

Q 13.

Arrange the following in increasing order of C—C bond length:  C2H & C2H4, C2H2.

Q 14.

Which gas is liberated in Kjeldhal’s method?

Q 15.

Which type of compounds are purified by steam distillation?

Q 16.

(a) What do you understand by Homolytic fission?
(b) What are carbanions? Give an example.

Q 17.

(a) Which is more suitable method for the purification of a compound in liquid state which decomposes at or below its boiling point?
(b) How will you separate a mixture of ammonium chloride and common salt?

Q 18.

The IUPAC name for
ncert-exemplar-problems-class-11-chemistry-chapter-12-organic-chemistry-some-basic-principles-2

(a) 1-Hydroxypentane-l, 4-dione
(b) 1,4-Dioxopentanol
(c) l-Carboxybutan-3-one
(d) 4-Oxopentanoic acid

Q 19.

Discuss the chemistry of Lassaigne’s test.

Q 20.

Name a suitable technique of separation of the components from a mixture of calcium sulphate and camphor.

Q 21.

Will CCl4 give white precipitate of AgCl on heating it with silver nitrate? Give reason for your answer.

Q 22.

Name three types of chromatography.

Q 23.

0.15 g of an organic compound gave 0.12 g of Ag Br by the Carius method. Find percentage of Br in the compound.

Q 24.

ncert-exemplar-problems-class-11-chemistry-chapter-12-organic-chemistry-some-basic-principles-4

(a) 1 -Chloro-2-nitro-4-methylbenzene
(b) l-Chloro-4-methyl-2-nitrobenzene
(c) 2-Chloro-1 -nitro-5-methylbenzene
(d) m-Nitro-p-chlorotoluene

Q 25.

In which of the following representations given below spatial arrangement of group/atom is different from that given in structure ‘A'?

ncert-exemplar-problems-class-11-chemistry-chapter-12-organic-chemistry-some-basic-principles-21

Q 26.

Which of the above compounds form pairs of metamers?

Q 27.

What are hybridisation states of each carbon atom in the following compounds?  CH2=C=O, CH3CH=CH2, (CH3)2CO, CH2=CHCN, C6H6.

Q 28.

Give the TUPAC names of the following compounds:

cbse-class-11th-chemistry-organic-chemistry-basic-principles-techniques-4

Q 29.

Explain the terms inductive and electromeric effects. Which electron displacement effect explain the following correct orders of acidity of the carboxylic acids?
(a) Cl3CCOOH > Cl2CHCOOH > ClCH2 COOH
(b) CH3CH2COOH > (CH3)2 CHCOOH > (CH3)3CCOOH

Q 30.

Which of the following carbocation is most stable?
cbse-class-11th-chemistry-organic-chemistry-basic-principles-techniques-45

Q 31.

How will you separate a mixture of Iodine and sodium chloride!

Q 32.

Write the name of element which is confirmed on adding Na2[Fe(CN)5NO] in sodium extract solution due to appearance of violet colouration.

Q 33.

Write the structural formula of 4-chloro-2-pentene.

Q 34.

Covalent bonds can undergo fission in two different ways. The correct representation involving the heterolytic fission of CH3 – Br is

ncert-exemplar-problems-class-11-chemistry-chapter-12-organic-chemistry-some-basic-principles-15

Q 35.

The addition of HC1 to an alkene proceeds in two steps. The first step is the attack of H+ ion to >C = C< portion which can be shown as

ncert-exemplar-problems-class-11-chemistry-chapter-12-organic-chemistry-some-basic-principles-17

 

Q 36.

Identify the pairs of compounds which are functional group isomers.

Q 37.

Identify the pairs of compounds that represent chain isomerism.

Q 38.

Which of the two: O2NCH2CH2O or CH3CH2O is expected to be more stable and why?

Q 39.

What type of solids are separated by fractional crystallisation?

Q 40.

What is the basic principle of chromatography?

Q 41.

(a) What is the basic principle involved in the estimation of nitrogen by Dumas method.
(b) In a Dumas nitrogen estimation method, 0.30 g of an organic compound gave 50 cm3 of N2 collected at 300 K and 715 mm Hg pressure. Calculate the percentage composition of nitrogen in the compound. (Vapour pressure of water at 300 K is 15 mm Hg)

Q 42.

Why is an organic compound fused with Sodium for testing nitrogen, halogens and sulphur?

Q 43.

Electronegativity of carbon atoms depends upon their state of hybridization. In which of the following compounds, the carbon marked with asterisk is most electronegative?
ncert-exemplar-problems-class-11-chemistry-chapter-12-organic-chemistry-some-basic-principles-6

 

Q 44.

In DNA and RNA, nitrogen atom is present in the ring system. Can Kjeldahl method be used for the estimation of nitrogen present in these? Give reasons.

Q 45.

If a liquid compound decomposes at its boiling point, which method(s) will you choose for its purification? It is known that the compound is stable at low pressure, steam volatile and insoluble in water.

Q 46.

Give three points of differences between inductive effect and resonance effect.

Q 47.

Why is nitric acid added to sodium extract before adding silver nitrate for testing halogens ?

Q 48.

Explain the reason for the fusion of an organic compound with metallic sodium for testing nitrogen, sulphur and halogens.

Q 49.

Why is it necessary to use acetic acid and not sulphric acid for acidification of sodium extract for testing sulphur by lead acetate test?

Q 50.

An organic liquid decomposes below its boiling point. How will you purify it?