NEET Chemistry Questions: Basic Principles of Orgainc Chemistry

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a-D-(+)-glucose and β-D-(+)-glucose are :





α-D-(+)-glucose and β-D-(+)-glucose are anomers. Anomers are stereoisomers that differ in the configuration around a specific carbon atom, typically the anomeric carbon atom in carbohydrates. They have the same molecular formula but different spatial arrangements.

The correct statement regarding electrophile is





(d) An electrophile is defined as electron deficient species which attacks on electron rich areas. Being electron deficient, the electrophiles behaves an Lewis acids.

e.g. H+, CI+, Br+, NO2+ NO+ etc.

The electrophiles can be seen in the form of neutral molecules also e.g. :CR2, N..R,BF3 etc.

Thus, we can say that electrophile can be either neutral or positively charged species and can form a bond by accepting a pair of electrons from a nucleophile.

With respect to the conformers of ethane, which of the following statements is true?





(d) Isomers which are possible by rotation about single bonds without cleavage of any bond are called conformers. In ethane, an infinite number of conformations are possible. There are two extreme forms, the staggered conformation, which is the most stable and the eclipsed conformation which is least stable. Among the conformers of ethane, bond angle and bond length remain same while their energy, stability and dihedral angle are different.

Which one is the correct order of acidity?





(b) Greater the s-character of C-atom in hydrocarbons, greater the electronegativity of

that carbon and thus greater the acidic nature of the H attached to electronegative carbon.

                        CH≡CH CH2=CH2 CH3-CH3

Hybridisation:         sp        sp2        sp3

s-character:          50%      33%       25%

Electronegativity:     ←Max.---------------------------------------

Acidic character      ←Max.---------------------------------------

of terminal H

Thus, CH≡CH > CH3C≡CH > CH2=CH2 > CH3-CH3

The most suitable method of separation of 1:1 mixture of ortho and para-nitrophenols is





(d) Steam distillation is used to purify the substances which

(i) are volatile in steam but are immiscible with water.

(ii) possess sufficiently high vapour pressure at the boiling point of water.

(iii) contain non- volatile impurities.

The process of steam distillation can also be used to separate a mixture of two organic compounds one of which is steam volatile while the other is not. In ortho and para-nitrophenols, the latter is non-volatile, hence they are separated by steam distillation.

The correct statement regarding the comparison of staggered and eclipsed conformations of ethane,is





The staggered conformation of ethane is more stable than the eclipsed conformation because it has no torsional strain. In the staggered conformation, the hydrogen atoms are arranged in a way that minimizes the steric repulsion between them, resulting in lower potential energy.

Some meta-directing substituents in aromatic substitution are given. Which one is most deactivating?





No explanation available.

Among the following compounds the one that is most reactive towards electrophilic nitration is





Toluene is the most reactive towards electrophilic nitration among the given options. The methyl group being an electron-donating substituent activates the benzene ring, making it more susceptible to electrophilic attack by the nitro group.

The correct order of decreasing acid strength of trichloroacetic acid (A), trifluoroacetic acid (B), acetic acid (C) and formic acid (D) is





The correct order of decreasing acid strength is: trifluoroacetic acid (B) > trichloroacetic acid (A) > formic acid (D) > acetic acid (C). The highly electronegative fluorine and chlorine atoms withdraw electrons, making the respective acids stronger than acetic and formic acids.

Which of the following does not exhibit optical isomerism?





No explanation available.

In Duma's method of estimation of nitrogen 0.35 g of an organic compound gave 55 ml of nitrogen collected at 300 K temperature and 715 mm pressure. The percentage composition of nitrogen in the compound would be

(Aqueous tension at 300 K-15 mm)





P1V1T1=P2V2T2 Here, P1=715-15=700 mm700×55300=760×V2273V2=46 ml at NTP% of N=2822400×volume ofN2 at NTPin mlweight of organic compound in g×100           =2822400×460.35×100=16.45

The Lassaigne's extract is boiled with con. HNO3 while testing for halogens. By doing so it





Actually, Na2S & NaCN are removed as H2S & HCN by conc. HNO3

Na2S+2HNO3→2NaNO3+H2SNaCN+HNO3→NaNO3+HCN

Among the given compounds, the most susceptible to nucleophilic attack at the carbonyl group is





(d) Key Idea Lesser the electron density of acyl carbon atom, more will be the susceptibility of nucleophile to attack it.

The Cl atom has strong -I effect and weakest +R effect because of the weak p-bond between the small sized C-atom and large sized Cl atom.

Thus, in CH3COCl, acyl carbon has least electron density and hence, more susceptible for nucleophilic attack.

The IUPAC name of the compound having the formula CH≡C-CH=CH2 is





(d) Double bond have preference over triple bond while naming CH≡C-CH=CH2
                                                                                       1-butene 3-yne

The relative reactivates of acyl compounds towards nucleophilic substitution are in the order of





No explanation available.