Chemistry MCQs and Short Questions

Question: What is the difference between classical and industrial chemistry?
Answer (Classical Chemistry): Essential for the science of chemistry by discovering and reporting new products, routes, and techniques.
Answer (Industrial Chemistry): Applies physical and chemical procedures for the transformation of natural raw materials into products useful for humans; is commercially used in society.
Note: Classical chemistry is not considered commercial.

Question: How is methyl orange prepared?
Answer: Obtained from sulphanilic acid by following steps.
Important Note: It acts as an indicator for acid-base titrations and changes colour according to the medium, yellow in basic and red in acidic.

Question: How is Fluorescent prepared?
Answer: Prepared by reacting phthalic anhydride with two moles of resorcinol via coupling.
Important Note: Commercially used as a dye.

Question: Enlist different chemicals produced from ethylene?
Answer: 1,2-Dichloroethane, Vinyl acetate, Ethylene oxide, Ethanol, Polyethylene

Question: What is the difference between thermoplastic and thermosetting polymers?
Answer (Thermoplastic): Soften on heating and harden on cooling, an example is PVC.
Answer (Thermosetting): Become more hard on heating and do not become soft when heated, an example is bakelite.

Question: How to synthesize Nylon 6,6 from 1,3 Butadiene?
Answer (Steps): The question details a series of chemical reactions starting with 1,3 butadiene, followed by various reactants (and reactions) to synthesize Nylon 6,6. The notes include the chemical formulas for understanding the transformations.

Question: What is chemical industry? Discuss different raw materials used in this industry?
Answer (Raw Material from Atmosphere): The atmosphere is a source for six industrial gases like NO2, O2, Ne, Ar, Kr, and Xe.
Answer (Raw Material from Hydrosphere): Ocean water is a source of salts like NaCl, Mg, and Br.
Answer (Raw Material from Lithosphere): The earth's crust is a source for mineral ores, carbon, and hydrocarbons like coal, natural gas, and crude petroleum.
Answer (Raw Material from Biosphere): Vegetation and animals contribute raw materials to industries producing oils, fats, waxes, resins, fibers, and leather.

Question: What are dyes? How are they classified on the basis of structures?
Answer: Dyes are colored compounds, typically used in solution to color fabrics; classified according to the type of chromophore present (e.g., Nitro, Azo, etc.).

Question: Discuss Vat Dyes?
Answer: Insoluble in water initially but become soluble on reduction with sodium hydrosulfide. The reduced dye forms a vat.
Important Note: Example is Indigo.

Question: Discuss Mordant Dyes?
Answer: They have no initial affinity for fabric, but bind via mordants (metal salts like chromium or aluminum) that create an insoluble complex with the fiber.

Question: Discuss Azoic Dyes?
Answer: Applied to fabric by treating it with a reagent (phenol or naphthol) in solution before a final treatment when the dye forms via coupling.

Answer: Insoluble in water but can be dispersed in a colloidal form in water. The fabric absorbs these dye particles.

Question: What are Pesticides? Describe its types in detail?
Answer: Chemicals to control pests (insects, mites, fungi, weeds, etc.).
Types: Insecticides, miticides, fungicides, herbicides, rodenticides, nematicides, molluscicides, repellents.

Question: Describe the basic building block in petrochemical technology?
Answer: Olefins (ethylene, propylene, butadiene); Aromatics (benzene, toluene, xylene); Synthesis gases (mixture of carbon monoxide and hydrogen).

Question: Describe raw materials and manufacturing processes of Nail Polish?
Answer: Raw materials include film-forming agents (e.g. nitrocellulose), resins and plasticizers (e.g., castor oil, fatty acids, and acetic acid), solvents (e.g., butyl stearate and acetate compounds), and a curing agent. The manufacturing process involves precisely measured ingredients, blending, dispersion and then pouring into molds.

Question: What are adhesives? Discuss its working and types?
Answer (Types): Natural adhesives (e.g., starch, resins, animal-based products), synthetic adhesives (e.g., elastomers, thermoplastics, thermosetting).
Answer (Working): Adhesives adhere because of intermolecular forces between bonding elements.