Chemistry

Organic Chemistry Fundamentals

287 Questions

Organic chemistry fundamentals cover the structure, properties, and reactions of carbon containing compounds. The questions explore functional groups, isomerism, homologous series, and basic reaction mechanisms. This forms the basis of general chemistry across multiple examination formats.

Functional groupsIsomerism typesHomologous seriesCycloalkanesOrganic monomers

Organic Chemistry Fundamentals Questions

Multiple choice

Epimerism is an isomerism that occurs depending on whcih of the following?

  1. Presence of asymmetric carbon atom.

  2. Spatial orientation of groups of single carbon atom.

  3. Orientation of H-OH group in C1 and C4.

  4. Rotation of plane of polarized light.

  5. Spatial arrangement of groups in asymmetric carbon atoms.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Difference in spatial orientation of groups on a single asymmetric carbon of a molecule having more than one asymmetric carbon. For example, glucose and galactose are 4 epimers of each other differing with respect to groups on C4.

Multiple choice

Which of the following statements is/are correct?

A. 1-Chloro-2,3-pentadiene has no chiral carbon atoms, yet it is a chiral molecule. B. A newly discovered compound is through to be chiral, but shows no rotation in a specific solvent. This means that the compound is assuredly achiral. C. When a chiral molecule reacts to give a chiral molecule, the product is always racemic.

  1. Only A

  2. Only B

  3. Only C

  4. A and C

  5. B and C
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This statement is correct because the molecule as whole is chiral since this molecule and its mirror image are non-superimposable.

Multiple choice

Which of the following statements is/are wrong?

A. 1-Methoxypropane and 2-methoxypropane are metamers. B. An optically active substance must be achiral. C. m-Chlorobromobenzene and m-bromochlorobenzene are isomers.

  1. A and B

  2. A and C

  3. B and C

  4. A, B and C

  5. Only A
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Statements A, B and C are incorrect. 1-Methoxypropane and 2-methoxypropane are positional isomers , an optically active substance must be chiral and  Isomers are molecules that have the same molecular formula, but have a different arrangement of the atoms in space.

Multiple choice

In the Carius method for quantitative elemental analysis, phosphorus in an organic compound is estimated in the form of ____________________.

  1. magnesia mixture

  2. ammonium phosphomolybdate

  3. phosphoric acid

  4. magnesium ammonium phosphate

  5. magnesium pyrophosphate
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Phosphorus present in an organic compound is estimated by Carius method. A known mass of the organic compound is heated with fuming nitric acid in a Carius tube for about 2 hours when P present in the compound is oxidised to phosphoric acid. It is precipitated as magnesium ammonium phosphate (Mg(NH4) PO4) by adding magnesia mixture (MgCl2, NH4Cl and a little aqueous NH3). The precipitate is filtered, washed, dried and then ignited to give magnesium pyrophosphate (Mg2P2O7). It is then weighed. From the masses of organic compound and magnesium pyrophosphate obtained, the percentage of P in the organic compound can be calculated.

Multiple choice

Which of the following sets represents the meta-directing functional groups?

  1. -OH, -NR2, -CH3

  2. -NO, -SO3H, -CHO

  3. -NO2, -CN, -NR2

  4. -NO, -SO3H, -NR2

  5. -OH, -NR2, -SO3H
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A monosubstituted benzene, when treated with an electrophile, undergoes electrophilic aromatic substitution reactions. Each reaction yields a disubstituted benzene as the organic product, which can be identified using the descriptors ortho, para and meta products. Common ortho and para directing groups are: -OH, -NR2, -CH3, -NR2 etc. Common meta directing groups are: -NO, -SO3H, -CHO, -NO2, -CN etc.

Multiple choice

Which among the following species is/are ortho and para directing group?

  1. –COCH3
  2. –SO3H
  3. –NR3+
  4. –OCH3

  1. Only 2

  2. Only 3

  3. Only 4

  4. 1 and 3

  5. 3 and 4
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Monosubstituted benzene when treated with an electrophile, undergoes electrophilic aromatic substitution reactions. Each reaction yields disubstituted benzene as the product, which can be identified using the descriptors ortho, para and meta as products. Common ortho and para directing groups are: -OH, -OCH3, -NR2, -CH3, -NR2 etc. Common meta directing groups are: -NO, -SO3H, -COCH3, -CHO, -NO2, -CN, -NR3+ etc. Hence, only –OCH3 group is ortho and para directing.

Multiple choice

C6H6 is

  1. benzene

  2. methane

  3. ethane

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

C6H6 is the molecular formula of benzene.

Multiple choice

Which of the following compounds measures the cetane number?

  1. Cyclopentadienyl manganese carbonyl

  2. n-hexadecane

  3. Tetraethyl lead

  4. Iso-octane

  5. (3) and (4) are correct
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

This option is correct because the cetane number is used for the measuring of the knocking character of the fuels in diesel engines and ignites very readily, hence this measures the cetane number.

Multiple choice

Which organic compound is a common component of fragrances?

  1. Benzofuran

  2. Furan

  3. Indole

  4. Aurone
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Indole is an aromatic heterocyclic organic compound. It has a bicyclic structure, consisting of a six-membered benzene ring fused to a five-membered nitrogen-containing pyrrole ring. Indole is a popular component of fragrances and the precursor to many pharmaceuticals.