Chemistry

Organic Chemistry

Question:

In an estimation of sulphur by Carius method, 0.468 of an organic sulphur compound gave 0.668 g of barium sulphate. Find the percentage of sulphur in the compound.

Answer:

Mass of the compound = 0.468 g
Mass of barium sulphate= 0.668 g
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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.

In which of the following compounds the carbon marked with asterisk is expected to have greatest positive charge?

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Q 3.

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

Q 4.

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 5.

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

Q 6.

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 7.

Under what conditions can the process of steam distillation is used?

Q 8.

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

Q 9.

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

Q 10.

Explain hyperconjugation effect. How does hyperconjugation effect explain the stability ofalkenes?

Q 11.

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 12.

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 13.

Discuss the principle of estimation of halogens, sulphur and phosphorus present in an organic compound.

Q 14.

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 15.

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

Q 16.

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

Q 17.

Write the hybridized state of C atoms in the following CH2 = CH – C-N

Q 18.

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

Q 19.

Which elements are estimated by Liebig’s Method?

Q 20.

0 .12 g of an organic compound containing phosphorous gave 0.22 g of Mg2 P2O7 by usual analysis. Calculate the percentage of phosphorous in the compound.

Q 21.

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 22.

Compounds with same molecular formula but differing in their structures are said to be structural isomers. What type of structural isomerism is shown by

ncert-exemplar-problems-class-11-chemistry-chapter-12-organic-chemistry-some-basic-principles-31

Q 23.

The structure of triphenylmethyl cation is given here. This is very stable and some of its salts can be stored for months. Explain the cause of high stability of this cation

Q 24.

Which of the following represents the correct TUPAC name for the compounds concerned?
(a) 2, 2-Dimethylpentane or 2-Dimethylpentane (b) 2, 4, 7-Trimethyloctane or 2, 5, 7- Trimethyloctane  (c) 2-Chloro-4-methylpentane or 4-Chloro-2-methylpentane (d) But-3-yn- l-ol or But-4-ol-yne.

Q 25.

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

Q 26.

Give a brief description of the principles of the following techniques taking an example in each  case: (a) Crystallisation (b) Distillation (c) Chromatography

Q 27.

Suggest a suitable technique for separating naphthalene from kerosene oil present in a mixture.

Q 28.

Name three types of chromatography.

Q 29.

Why is an organic compound fused with sodium in Lassaigne’s test?

Q 30.

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 31.

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

Q 32.

How will you detect the presence of nitrogen and sulphur in Lassaigne’s extract?

Q 33.

Explain why (CH3)3C+ is more stable than CH3C+H2.

Q 34.

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 35.

Identify the pairs of compounds which are functional group isomers.

Q 36.

Resonance structures of propenal are given below. Which of these resonating structures is more stable? Give reason for your answer.
ncert-exemplar-problems-class-11-chemistry-chapter-12-organic-chemistry-some-basic-principles-46
 

Q 37.

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

Q 38.

What are electrophiles and nucleophiles? Explain with examples:

Q 39.

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

Q 40.

Explain, why an organic liquid vaporises at a temperature below its boiling point in its steam distillation ?

Q 41.

cbse-class-11th-chemistry-organic-chemistry-basic-principles-techniques-26

Q 42.

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

Q 43.

Which gas is liberated in Kjeldhal’s method?

Q 44.

Which method is used to extract a compound in aqueous solution?

Q 45.

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

Q 46.

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

Q 47.

cbse-class-11th-chemistry-organic-chemistry-basic-principles-techniques-35

Q 48.

Ionic species are stabilized by the dispersal of charge. Which of the following carboxylate ions is the most stable?

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Q 49.

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 50.

Which of the above compounds form pairs of metamers?