Organic Chemistry – Some Basic Principles and Techniques NEET MCQ

1. Which among the following is an unsaturated hydrocarbon?

a) Methane
b) Ethene
c) Propane
d) Butane

Answer:

b) Ethene

Explanation:

Ethene (C2H4) contains a double bond, making it an unsaturated hydrocarbon.

2. The IUPAC name for CH3COCH3 is:

a) Propanal
b) Methanone
c) Ethanol
d) Propanone

Answer:

d) Propanone

Explanation:

CH3COCH3 is a ketone with three carbons, hence named as Propanone.

3. The hybridization of the carbon in methane is:

a) sp
b) sp2
c) sp3
d) dsp3

Answer:

c) sp3

Explanation:

Methane (CH4) has tetrahedral geometry, and the carbon is sp3 hybridized.

4. Which functional group is present in alcohols?

a) -CHO
b) -COOH
c) -OH
d) -CN

Answer:

c) -OH

Explanation:

Alcohols have a hydroxyl (-OH) functional group.

5. Which isomer of pentane has a branched chain?

a) n-pentane
b) iso-pentane
c) neo-pentane
d) None of the above

Answer:

b) iso-pentane

Explanation:

iso-pentane has a branched chain, while n-pentane has a straight chain.

6. Which of the following shows tautomerism?

a) Ethene
b) Ethyne
c) Acetone
d) Acetaldehyde

Answer:

d) Acetaldehyde

Explanation:

Acetaldehyde can exist in enol and keto forms due to tautomerism.

7. The process of purification used for separating a solid from a solution is:

a) Distillation
b) Sublimation
c) Crystallization
d) Chromatography

Answer:

c) Crystallization

Explanation:

Crystallization is a process of purification used to separate a pure solid from a solution.

8. Which spectroscopy is based on the absorption of ultraviolet and visible light?

a) IR spectroscopy
b) NMR spectroscopy
c) UV-Vis spectroscopy
d) Mass spectroscopy

Answer:

c) UV-Vis spectroscopy

Explanation:

UV-Vis spectroscopy is based on the absorption of ultraviolet and visible light.

9. In which reaction type, an atom or group of atoms is replaced by another atom or group of atoms?

a) Addition reaction
b) Elimination reaction
c) Substitution reaction
d) Polymerization

Answer:

c) Substitution reaction

Explanation:

In a substitution reaction, one atom or group of atoms replaces another atom or group of atoms in a molecule.

10. The number of sigma and pi bonds in ethene are:

a) 5 sigma, 1 pi
b) 4 sigma, 2 pi
c) 6 sigma, 0 pi
d) 3 sigma, 1 pi

Answer:

a) 5 sigma, 1 pi

Explanation:

Ethene (C2H4) has 5 sigma and 1 pi bond.

11. Which molecule has zero dipole moment?

a) H2O
b) CO2
c) NH3
d) HCl

Answer:

b) CO2

Explanation:

CO2 is a linear molecule, and its dipole moments cancel out, resulting in a net dipole moment of zero.

12. The IUPAC name of CH3-CH2-COOH is:

a) Methanoic acid
b) Ethanoic acid
c) Propanoic acid
d) Butanoic acid

Answer:

c) Propanoic acid

Explanation:

The compound has three carbons with a carboxylic acid group, hence named Propanoic acid.

13. The phenomenon where an electron pair donor is called a:

a) Lewis acid
b) Bronsted acid
c) Lewis base
d) Bronsted base

Answer:

c) Lewis base

Explanation:

A Lewis base donates an electron pair.

14. The bond formed as a result of the overlap of two p-orbitals is:

a) Sigma bond
b) Pi bond
c) Coordinate bond
d) Hydrogen bond

Answer:

b) Pi bond

Explanation:

A pi bond is formed due to the sideways or lateral overlap of two parallel p-orbitals.

15. Which compound will not decolorize bromine water?

a) Ethene
b) Ethane
c) Styrene
d) Cyclohexene

Answer:

b) Ethane

Explanation:

Ethane is a saturated hydrocarbon and does not undergo addition reactions with bromine water.

16. The geometry of methane molecule is:

a) Linear
b) Bent
c) Tetrahedral
d) Trigonal planar

Answer:

c) Tetrahedral

Explanation:

Methane (CH4) has a tetrahedral geometry due to the sp3 hybridization of carbon.

17. Which of the following is a primary amine?

a) CH3NHCH3
b) (CH3)2NH
c) (CH3)3N
d) C6H5NH2

Answer:

d) C6H5NH2

Explanation:

C6H5NH2 is aniline, which is a primary amine.

18. The C=O bond is found in:

a) Alcohols
b) Aldehydes
c) Ethers
d) Amines

Answer:

b) Aldehydes

Explanation:

The carbonyl group (C=O) is characteristic of aldehydes and ketones.

19. The principle involved in paper chromatography is:

a) Sublimation
b) Adsorption
c) Distillation
d) Solubility

Answer:

b) Adsorption

Explanation:

The separation in paper chromatography is based on the adsorption of substances on paper.

20. Which of the following will exhibit geometrical isomerism?

a) But-1-ene
b) But-2-ene
c) Cyclohexene
d) Methyl propene

Answer:

b) But-2-ene

Explanation:

Geometrical isomerism requires the presence of a double bond between two carbon atoms with two different groups/atoms attached to them. But-2-ene fulfills this criteria.

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