Science Group
Explore subjects and practice MCQs
7
Chapters
1,610
Total MCQs
Science Group
Answer: Phenol is highly activated toward electrophilic substitution. Bromine water (no catalyst needed) brominates all three ortho/para positions, forming 2,4,6-tribromophenol as a white precipitate.
Answer: Cell efficiency is the ratio of actual (measured) voltage to the theoretical (standard) voltage expressed as a percentage, accounting for internal resistance and overpotential.
Answer: The Beckmann rearrangement converts ketoximes to amides/lactams via alkyl migration. Cyclohexanone oxime rearranges to caprolactam, the monomer for Nylon-6.
Answer: After proton activation of the carbonyl, the slowest step is the nucleophilic addition of the alcohol to form the tetrahedral intermediate.
Answer: The tetraamminecopper(II) complex [Cu(NH3)4]2+ has a deep blue (royal blue) color due to d-d transitions in the square planar complex with NH3 as ligand.
Answer: PCl5 converts alcohols to alkyl chlorides: C2H5OH + PCl5 -> C2H5Cl + POCl3 + HCl. The OH group is replaced by Cl.
Answer: Chlorine is electron-withdrawing (inductive effect). More Cl atoms increase acidity by stabilizing the conjugate base (carboxylate anion) through electron withdrawal.
Answer: SN2 proceeds with Walden inversion: the nucleophile attacks from the back side of the C-Br bond, inverting the stereochemistry from (R) to (S).
Answer: Maximum stereoisomers = 2^n where n is the number of chiral centers. However, meso compounds may reduce this number if the molecule has internal symmetry.
Answer: Hot KMnO4 oxidizes any alkyl group on benzene (with at least one benzylic H) to -COOH, producing benzoic acid regardless of the alkyl chain length.
Answer: Biology comes from the Greek words bios (life) and logos (study), so it deals with life and living organisms.
Answer: The word Biology is derived from two Greek words: bios meaning life and logos meaning study or thought.
Answer: Biology is made up of bios (life) and logos (study), so it literally means the study of life.
Answer: Zoology is the branch of biology concerned with the study of animals.
Answer: Botany deals with the study of plants, including their structure, growth and reproduction.
Answer: Microbiology is the study of microscopic organisms including bacteria, viruses and fungi.
Answer: Jabir ibn Hayyan is regarded as the Father of Chemistry due to his pioneering experimental work in the field.
Answer: Ibn Nafis described the pulmonary circulation of blood long before it was described in Europe.
Answer: The cell is the basic structural and functional unit of all living organisms.
Answer: Several tissues grouped together form an organ.