Question 1

The number of geometrical isomers possible for the compound, CH _3 CH = CH - CH = CH _2 is

Accepted Answer

Although CH _3 C = CH - CH = CH _2 has two double bond but one of them has two similar atoms (i.e. H -atom) therefore no geometrical isomerism is possible around the double bond. However each carbon atom of other double bond has two different atoms/groups and hence geometrical isomerism is possible around this double bond. Hence, only two geometrical isomers are possible.

Question 2

Correct order of stability of carbanion is

Accepted Answer

As we know compound (4) is aromatic and the compound (1) is anti-aromatic. Hence compound (4) is most stable and compound (1) is least stable among these in compound (2) and (3) carbon atom having charge is sp ^3 hybridised. On the basis of angle strain theory compound (3) is more stable than compound (2).

Question 3

Which of the following is not correct about Grignard reagent?

Accepted Answer

Grignard reagent = R - + Mg - X

Question 4

The IUPAC name of the following molecule is

Accepted Answer

- NO _2 and -Cl are written as prefixes with CH _3 being given the highest preference for numbering ( C -1). Thus, the name of the compound will be 2- chloro-1-methyl-4-nitrobenzene.

Question 5

Choose the correct stability order of the given free radicals.

Accepted Answer

In compounds (I), (III) and (IV) the -M effect and hyperconjugation effect are inoperative at meta positions. So we should consider the inductive effect of the groups. -I effect will decrease the stability of the free radical by withdrawing the electrons toward it itself. The order of -I effect is $ NO _2> CN > OH $. Therefore (III) is most destabilised. In compound (II) the OH act as electron donating group through +M effect which is operative at para position. This increase the electron dens

Question 6

Which of the following is strongest Bronsted base?

Accepted Answer

Answer option index: 3

Question 7

Which of the following acts as the stationary phase in paper chromatography?

Accepted Answer

Chromatography paper contains water trapped in it, which acts as the stationary phase.

Question 8

Which one of the following exhibits geometrical isomerism?

Accepted Answer

Alkenes having double bonds with two different groups on each end of the double bond show geometrical isomerism. A_2 b_2 c_2, A_2 b_2 c d, A_2 bcde.

Question 9

Geometrical isomerism is not shown by

Accepted Answer

The condition for geometrical isomerism is CH _2= C ( Cl ) CH _3 does not follow above mention condition.

Question 10

For the separation of two immiscible liquids which method is used?

Accepted Answer

Separating funnel is used when the two liquids are immiscible.

Question 11

Which of the following factors affect the basic strength of amine? (i) Inductive effect (ii) Steric hinderance (iii) Solvation effect (iv) Solubility in organic solvents.

Accepted Answer

Inductive effect, steric hinderance and solvation effect the basic strength of amines.

Question 12

Ninhydrin gives yellow colour in paper chromatography with which amino acid?

Accepted Answer

The amino acid which gives yellow colour with ninhydrin in paper chromatography is proline. Ninhydrin + Proline Yellow-orange product

Question 13

0.20 ~g of an organic compound gave 0.12 ~g of AgBr By using Carius method, the percentage of bromine in the compound will be

Accepted Answer

Given, Mass of an organic compound =0.20 ~g Mass of AgBr =0.12 ~g Molecular mass of AgBr =188 ~g ~mol ^ -1 188 ~g of AgBr contains 80 ~g of bromine 0.12 ~g of AgBr will contain = 80 188 0.12 =0.05 ~g of bromine Percentage of bromine = 0.05 0.20 100 =25 \%

Question 14

The correct stability order of following species is -

Accepted Answer

x has a conjugated diene system, w an isolated diene system, z a cumulated diene system, and y an antiaromatic system.

Question 15

The Lassaigne's extract is boiled with dil. HNO _ 3 before testing for halogens because

Accepted Answer

Na _ 2 ~S and NaCN , formed during fusion with metallic sodium, must be removed before adding AgNO _ 3 , otherwise black ppt. due to Na _ 2 ~S or white precipitate due to AgCN will be formed and thus white precipitate of AgCl will not be identified easily. Na _ 2 ~S +2 AgNO _ 3 2 NaNO _ 3 + Black Ag _ 2 ~S NaCN + AgNO _ 3 NaNO _ 3 + White Ag CN NaCl + AgNO _ 3 NaNO _ 3 + White Ag Cl Na _ 2 ~S +2 HNO _ 3 boil 2 NaNO _ 3 + H _ 2 ~S NaCN + HNO _ 3 boil NaNO _ 3 + HCN

Question 16

Maleic acid and fumaric acids are

Accepted Answer

Maleic acid and fumaric acids are geometrical isomers.

Question 17

Br ^ will abstract which of the hydrogen most readily?

Accepted Answer

Bromine is more selective abstract that hydrogen which forms stable free- radical

General Organic Chemistry — Previous Year Questions & Solutions