All Free Chemistry MCQs with Answers

• A. Aniline
• B. Pyridine
• C. Hydrazine
• D. Naphthalene

Explanation: Option D is correct as it is an aromatic hydrocarbon containing two fused benzene rings with the formula C10H8 hence it does not contain…

• A. CaCO3
• B. CAC2
• C. KCN
• D. (NH2)CO

Explanation: (NH2)CO (urea): This compound is organic as it contains carbon-hydrogen (C-H) bonds and is commonly found in biological systems.

• A. Multiple bonds
• B. Hybridization
• C. Long chain or rings of carbon atom
• D. Showing isomerism

Explanation: C (long chain or rings of carbon atom) is the correct answer as it specifically describes the process of catenation, where carbon atoms…

• A. (H₂N)2CO
• B. NH4CNO
• C. CH₂NO₂
• D. CH4

Explanation: The correct answer is ammonium cyanate (NH4CNO), which is not considered an organic compound as it lacks carbon-hydrogen (C-H) bonds, a…

• A. 2 Hydrogens
• B. 2 Carbons
• C. 3 Carbons
• D. 4 Carbons

Explanation: A tertiary carbon is a carbon atom bonded directly to three other carbon atoms.

• A. Electrophilic addition
• B. Electrophilic substitutions
• C. Free radical substitutions
• D. All are possible

Explanation: Chemical reactions associated with hydrocarbons are:Electrophilic addition, Electrophilic substitutions, Free radical substitutions.

• A. Natural gas
• B. Petroleum
• C. Coal
• D. Ammoniacal Liquor

Explanation: Ammoniacal liquor is an organic compound. It is a concentrated solution of ammonia, ammonium compounds, and sulfur compounds, obtained as…

• A. Homocyclic compounds
• B. Heterocyclic compounds
• C. Alicyclic compound
• D. Aromatic homocyclic compounds

Explanation: Thiophene is indeed a heterocyclic compound. It consists of a ring structure made up of four carbon atoms and one sulfur atom.

• A. Peat
• B. Urea
• C. Sugar
• D. Alcohol

Explanation: The first organic compound prepared in the laboratory was urea. Urea was synthesized by Friedrich Wöhler in 1828 from inorganic starting…

• A. Hydrocarbons
• B. Homocyclic
• C. Alicyclic
• D. Heterocyclic

Explanation: Pyrole is a heterocyclic compound. Heterocyclic compounds are organic compounds with a ring structure that contains in the cycle at least…

• A. ɑ-amino acids
• B. β-amino acids
• C. Both ɑ and β
• D. None of the above

Explanation: The correct answer is that all amino acids found in proteins are ɑ-amino acids.

• A. Three polypeptide chains
• B. Four polypeptide chains
• C. Five polypeptide chains
• D. Six polypeptide chains

Explanation: Haemoglobin is a quaternary structure therefore its composed of four polypeptide chains, 2 alpha globins and 2 beta globins.

• A. Protein
• B. Carbohydrate
• C. Lipid
• D. Vitamins

Explanation: Proteins are large biomolecules composed of amino acids linked together by peptide bonds.

• A. Heat
• B. Change in pH
• C. Heavy metal salts
• D. All of the above

Explanation: Heavy metal salts interact with proteins causing a change in their tertiary structure which leads in the denaturation of protein

• A. Conjugated proteins
• B. Simple proteins
• C. Both (A) & (B)
• D. None of the above

Explanation: Albumin is an example of a conjugated protein. It is a type of protein that is combined (or conjugated) with a non-protein component…

• A. Primary structure
• B. Secondary structure
• C. Tertiary structure
• D. Quaternary structure

Explanation: Enzymes have a three-dimensional shape due to their tertiary structure.

• A. Primary structure
• B. Secondary structure
• C. Tertiary structure
• D. Quaternary structure

Explanation: The protein present in hemoglobin has a tertiary structure. Hemoglobin is a globular protein composed of four polypeptide chains (two…

• A. 0.2 M urea
• B. 0.1 M Glucose
• C. 0.1 M MgSO4
• D. 0.1 M BaCl2

Explanation: The higher the vanthoff factor, the greater the lowering of vapor pressure.

• A. 15.2 torr
• B. 17.8 torr
• C. 23.8 torr
• D. 29.7 torr

Explanation: Mole fraction of the solute = xs = 0.25Pressure of the solvent = PH2O = 23.76 torrFirst, we solve for the mole fraction of the…

• A. No change in its freezing point and boiling point
• B. Freezing point increases and boiling point decreases.
• C. Freezing point increases and boiling point increases
• D. Freezing point decreases and boiling point increases

Explanation: The presence of impurities in a substance lowers the melting point but increases the boiling point of the substance.