JEE Questions for Chemistry Organic Chemistry Some Basic Principles And Techniques Quiz 3 - MCQExams.com

Number of optically  active stereomers = 2 ^n-1 = 2^2-1 = 2

CH₃OCH₃ and CH₂ CH₂OH have different functional groups but have same molecular formula. So these are functional isomers.

If same group of atoms attached with double bond bearing carbon, then alkene does not show geometrical iosmerism

The different arrangement of  atoms in space that results from the carbon –carbon single bond free rotation by 360⁰ are conformational. Isomers and this phenomenon is called conformational isomerism.

CH₃CH₂OH has intermolecular H-bonding. So, larger heat is required to vapourise. CH₃CH₂OH as compound to CH₃OCH₃. Also CH₃CH₂OH is less volatile than CH₃OCH₃ thus vapour pressure are different. So, (a) and (b) is incorrect.

Boiling point of  CH₂OH > CH₃OCH₃, thus (c) is also incorrect.

Density is equal to mass per unit volume due to ideal behaviour at a given temperature and pressure, volume and molar mass are same. Hence they have same vapour density

Gauche conformation is more stable due to hydrogen linkage in between F and H so, order is eclipse, anti, Gauche

n pentane and 2-methyl butane are constitutional isomers are chain isomers or skeletal isomers

The isomerism which arises due to rotation about a C–C is called conformational isomerism and the isomers are called conformational isomers or conformers.

2-pentanons and 3-methyl-2 butanonl are chain isomers because they differ in carbon skeleton

When –OH group of lactic acid is replaced by H, chiral carbon is lost. So its optical activity is lost.

In structure of 1,chloro-2-nitroethene is as in this compound, E-2 isomerism is possible because it is highly substituted alkene.

Aniline is a steam volatile compound. Those organic compounds which are volatile in steam are purified by steam distillation so aniline is purified by distillation

Chromatography is a technique used for the separation of mixtures into its components purification of compounds and also to the test the purity of compound

Distillation is used to purify liquids and based on difference in their boiling points. When boiling points of liquids are very closed to each others then fractional distillation is used.

Benzoic acid , Camphor and napthalene sublime on heating . So, they are purified by sublimation method.

To separate benzoic acid from its mixture with camphor aquous solution of NaHCO₃ is used Benzoic acid from water soluble sodium benzoate with NaHCO₃. While camphore do not react with NaHCO₃ followed by differential extraction of solvent .

Aqueous HCl is used to separate aniline and nitrobenzene. Aniline reacts with HCl to form salt which is water soluble. Nitrobenzene does not react with HCl

To estimate nitrogen atom present in an organic compound; Kjeldahl’s method is used. In this method organic compund is heated with conc. H₂SO₄ is presence of K₂SO₄ and CuSO₄, the nitrogen present in the compound is converted into amonium sulphate 

% of ¹²C → 52

% of ¹H → 13

% of ¹⁶O = [100-(52+13)] = 100 – 65 = 35

Number of ¹²C atom = 52/12 = 4.33

No. of ¹H atom = 13/1 = 13

No. of ¹⁶O atom = 35/16 = 2.18

Simple ratios of

         C     :        H     :     O

4.33/2.18 :  13/2.18  : 2.18/2.18

   1.98       :    5.96     :     1

      2         :      6        :      1

∴ Empirical formula = C₂H₆O

Empirical weight = (212) + (61) + 16 = 46g

Molecular weight = 2 VD = 223 = 46

n = 46/46 = 1

∴ Molecular formula of the compound = C₆H₆O 

Compound reacts with Na to liberate H₂

∴ Compound is H₃C – CH₂ – OH

∴ A functional isomer of ethanol is H₃C – O – CH₃

Hence the compound is methoxy methane.

Compound is carbon tetrachloride (CCl₄) as on heating  with CuO, CO₂, is produced and does not produce water so it contains carbon and  but not hydrogen

NH₂ – NH₂ – HCl does not give Lassaigne’s test as it does not contains carbon. Lassaigne’s test is given by only those nitrogenous compounds in which both carbon and nitrogen is present

Presence of halogen in organic compound can be detected by beilstein’s test.

Halogens containing compounds (C₆H₅Cl) when placed in a flame, the presence of halogen is revealed by a green to blue flame 

In S_N1 reaction, the racemisation takes place due to inversion and retention of configuration.

In S_N1 reaction depends upon the concentration of the substrate only. In this type of reaction, covalent neuclophile reacts on substrate. 2⁰ and 3⁰ alkyl halide react through this mechanism.

Rate of reaction depends upon the concentration of both reactant and neuclophile, it is a S_N2 reaction. It involves inversion of configuration

Hydride ion is formed when hydrogen atom accept an electron, so it has tendency to donate electron. Since H^– has a tendency to donate electron, it functions as neucleophile

Alcohols undergo dehydration usually by EI mechanism. This is because elimination is preferred in case of tertiary alcohols.

Ketone undergoes nucleophilic addition reaction because nucleophilic end of reagent attack first followed by electrophilic end of reagent.

H₂O, ROH, R–COOH are protic solvent because they are polar in nature and contain a hydrogen directly bonded to oxygen while other are aprotic solvent. They are favourable for S_N1reactions. While aprotic solvents are favourable for S_N2 reactions.