NEET Chemistry Questions: Basic Principles of Orgainc Chemistry

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How many isomers could be obtained from the alkane, C6H14?





No explanation available.

2-methylpent-3-ene is a chiral because it has:





2-methylpent-3-ene does not have a center or plane of symmetry. It has a chiral carbon (C2) due to the presence of four different groups attached to it, making the molecule chiral or optically active.

The (R)- and (S)-enantiomers of an optically active compound differ in





(c) R and S forms of an optically active compounds differ in their behaviour towards plane polarised light. The species which rotate the plane of polarised light toward right is called R-form (rectus form) or d-form (dextro-form) and the species which rotate the plane of polarised light towards left is known as S-form (sinister-form) or L-form (laevo-form).

The cylindrical shape of an alkyne is due to 





(d) In alkynes C≡C is present, in such bond one sigma and two π C-C bonds are present. Sigma bond is formed by sp-hybrid orbitals whereas π-bonds are formed by unhybridised orbitals.

Hence, it shows cylindrical shape.

What is decreasing order of basicity of 1°, 2° and 3° ethyl amines and ammonia?          





(d) As the number of alkyl groups increases, the electron density on nitrogen atom also increases, so the basic character increases but 3° amines are less basic than 2° amines due to steric hindrance of 3° amines, so the correct order of basicity is

 Ammonia < 1 < 2 <3

 NH3<C2H5NH2<(C2H5)3N<(C2H5)2NH

The shortest C-C bond distance is found in               





(d) Acetylene has shortest C-C bond length because it has C≡C triple bond. The bond length follows the following order

   C-C>C=C>C≡C

Which of the following is more basic than aniline?                    





(d) Benzyl amine, C6H5CH2-N..H2 is more basic than aniline because benzyl group (C6H5CH2-) is electron donating group due to +I-effect. So, it is able to increase the electron density of N of -NH2 group. Thus, due to higher electron density, rate of donation of free pair of electron is increased, i.e. basic character is hhigher. Phenyl and nitro group are electron attractive groups, so they are able to decrease the electron density of N of -N..H2 group. Hence, they are less basic than aniline.

Which one of the following has the shortest carbon-carbon bond length?                      





(c) Ethyne (acetylene) have shortest C-C bond length because it has CC bond. The bond length follows the following order

       CC <C=C<C-C

Which of the following represents the correct order of acidity in the given compounds?





(c) The acidity of halogenated acid increases with increase in electronegativity of the halogen present. So,  the correct order is order is F > Ce >Br

 FCH2COOH > ClCH2COOH > BrCH2COOH > CH3COOH

Ethanol and dimethyl ether form a pair of functional isomers. The boiling point of ethanol is higher than that of dimethyl ether due to the presence of





Ethanol has a hydroxyl (-OH) group that can participate in hydrogen bonding, whereas dimethyl ether does not have any hydrogen atoms attached to highly electronegative atoms. This intermolecular hydrogen bonding in ethanol results in stronger attractive forces, leading to a higher boiling point.

Among the following the strongest acid is                                 





(c) We know that, inductive effect decreases rapidly with distance. Inductance effect distance depending factor. As the distance of Cl-atom increases the acidic character decreases.

The distance between two adjacent carbon atoms is largest in





(c) The C-C bond length is maximum for single bond, so butane have largest C-C bond length because it contains carbon-carbon single bond.

Which of the following represent the correct decreasing order of acidic strength of following? 

(i) Methanoic acid

(ii) Ethanoic acid

(iii) Propanoic acid

(iv) Butanoic acid





The acidic strength of carboxylic acids decreases with an increase in the size of the alkyl group. This is because the larger alkyl groups have a greater electron-releasing or electron-donating effect, which decreases the polarity of the O-H bond, making it less acidic. Therefore, the correct decreasing order of acidic strength is: methanoic acid > ethanoic acid > propanoic acid > butanoic acid.

The relative stability order of carbanions CH≡C-, CH- and CH2=CH- is ____________





As the electronegativity of the atom at which -ve charge is present, the stability of the carbanion also increases. The order is

CHC->CH2=CH->CH3-

 

Trans-2-butene on bromination using CS2 gives which dibromoderivative





Addition of Br2 in alkene is an example of anti addition. Trans alkene on anti addition give meso compound.