All Free Biology MCQs with Answers

• A. Photochemistry
• B. Sonochemistry
• C. Nuclear chemistry
• D. Biochemistry

Explanation: Under the green chemistry such chemical products are designed that can reduce the use or production of hazardous substances. Nuclear chemistry deals with radioactivity, nuclear processes etc. that are not safe for our environment so it is not the part of green chemistry.

• A. Sedatives
• B. Antiseptics
• C. Antipyretic
• D. Antidepressant

Explanation: Antipyretics are drugs that help reduce fever. Common examples include acetaminophen (paracetamol) and nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen. These drugs work by influencing the hypothalamus in the brain, which regulates body temperature.

• A. Sodium stearate
• B. Sodium stearoyl lactylate
• C. Sodium acetate
• D. Sodium benzoate

Explanation: Sodium stearate is a salt of stearic acid, which is a fatty acid. It is a common ingredient in soap and is often used as a surfactant, helping to emulsify and solubilize oils and fats. So, sodium stearate is indeed an ingredient found in ordinary soap.

• A. Esterification
• B. Saponification
• C. Acetylation
• D. Carboxylation

Explanation: The alkaline hydrolysis of oils and fats is called Saponification. The ester, on treating with a base such as NaOH is converted back to alcohol and sodium salt of carboxylic acid. The reaction is known as saponification because it is used in the manufacture of soap.

• A. Palmitic acid
• B. Stearic acid
• C. Lauric acid
• D. Benzoic acid

Explanation: Benzoic acid is not typically used in soap preparation.It is an aromatic carboxylic acid and is not a common ingredient in traditional soap-making processes.

• A. Both are fatty acids having same number of carbon atoms
• B. Both are saturated fatty acids
• C. One olefinic bond is present in oleic acid
• D. The alkyl group of stearic acid contains 38 hydrogen atoms

Explanation: Stearic acid is a saturated fatty acid, as it contains no double bonds in its hydrocarbon chain. On the other hand, oleic acid is a monounsaturated fatty acid, possessing one double bond in its hydrocarbon chain.Hence, the statement given in option 'B' is incorrect making it the correct answer.

• A. It is a drying oil
• B. It is used in paints and varnishes
• C. It is a vegetable oil
• D. All of these are correct

Explanation: Upon review, all the statements (a, b, and c) individually appear to be accurate descriptions of linseed oil. Therefore, based on the options provided, it appears that none of the statements are incorrect making option 'd' correct.

• A. Stearic acid
• B. Octadecyl alcohol
• C. Tricarboxylic acid
• D. Heptadecyl alcohol

Explanation: Hydrogenolysis of tristearin involves breaking the ester bonds between glycerol and the stearic acid chains. As a result, the primary product formed is often fatty alcohols. In this case, octadecyl alcohol, also known as stearyl alcohol, is a probable product of the hydrogenolysis of tristearin.

• A. Oleic acid
• B. Glycerol
• C. Stearic acid
• D. Tristearin

Explanation: Hydrogenolysis is a chemical reaction that involves the cleavage or breaking of chemical bonds in a molecule using hydrogen gas (H2) in the presence of a suitable catalyst.Catalysts commonly used in hydrogenolysis reactions include metals such as platinum (Pt), palladium (Pd), nickel (Ni), and other transition metals.When hydrogen adds to all of the double bonds of glyceryl trioleate (triolein) using a nickel catalyst, the product is the saturated fat glyceryl tristearate (tristearin).

• A. Glycerol tristearate
• B. Cetyl palmitate
• C. Melissylcerotate
• D. Melissyl palmitate

Explanation: Glycerol tristearate is a white microfine crystalline powder whereas all others are white waxy solids.