Chem lab quiz EXAM TEST BANK WITH ALL VERSIONS OF THE EXAM WITH ALLMODULES COVERED | ACCURATE AND VERIFIED QUESTIONS AND ANSWERS FOR GUARANTEED PASS| LATEST UPDATE

Why is the reaction of ethene with bromine called an addition reaction? A) Because bromine breaks into ions in water B) Because ethene is removed during the reaction C) Because bromine atoms add across the double bond of ethene D) Because it causes a color change in the solution Correct answer: C Rationale: In an addition reaction, atoms are added to a molecule without removing any atoms. Bromine adds across the double bond in ethene, forming a saturated product. If you used a bromine test to distinguish between hexane and 2-hexene, in which would the red color of bromine persist? A) 2-hexene B) Hexane C) Both D) Neither Correct answer: B Rationale: Hexane is a saturated hydrocarbon and does not react with bromine, so the red color persists. 2-hexene is unsaturated and reacts with bromine, causing the color to disappear. If you used a permanganate test to distinguish between hexane and 1-hexene, in which would the purple color of KMnO₄ persist? A) 1-hexene B) Hexane C) Both D) Neither Correct answer: B Rationale: Hexane is saturated and does not react with KMnO₄, so the purple color remains. 1hexene is unsaturated and reacts, changing the solution color from purple to brown. What is the functional group for alcohols? A) -COOH B) -OH C) -NH₂ D) -CH₃ Correct answer: B Rationale: Alcohols contain a hydroxyl (-OH) functional group. Why are some alcohols soluble in water? A) Because they are non-polar B) Because they are ionic compounds C) Because they contain carbonyl groups D) Because they form hydrogen bonds with water Correct answer: D Rationale: Alcohols with short hydrocarbon chains can form hydrogen bonds with water, making them soluble. Classify 1-propanol: A) Primary alcohol B) Secondary alcohol C) Tertiary alcohol D) Phenol Correct answer: A Rationale: 1-propanol has the -OH group attached to a carbon that is bonded to only one other carbon, making it a primary alcohol. Classify 3-pentanol: A) Primary alcohol B) Secondary alcohol C) Tertiary alcohol D) Phenol Correct answer: B Rationale: In 3-pentanol, the -OH group is on a carbon attached to two other carbon atoms, classifying it as secondary. Classify 2-methyl-2-butanol: A) Primary alcohol B) Secondary alcohol C) Tertiary alcohol D) Phenol Correct answer: C Rationale: The central carbon bearing the -OH group is attached to three other carbon atoms, making it a tertiary alcohol. If you add chromate to 1-propanol, will a green Cr³⁺ solution be formed? A) Yes B) No C) Only in acidic solution D) Only in basic solution Correct answer: A Rationale: 1-propanol is a primary alcohol and undergoes oxidation by chromate, forming a green Cr³⁺ solution as a positive test. If you add chromate to 2-methyl-2-butanol, will a green Cr³⁺ solution be formed? A) Yes B) No C) Only in heat D) Only if diluted Correct answer: B Rationale: Tertiary alcohols like 2-methyl-2-butanol do not undergo oxidation with chromate, so the color remains unchanged. If an alcohol solution has a pH of 5, what type of compound is it likely to be? A) Primary alcohol B) Secondary alcohol C) Tertiary alcohol D) Phenol Correct answer: D Rationale: Phenols are weakly acidic and can slightly ionize in water, resulting in a pH around 5. Alcohols are generally neutral. Which alcohol is classified as a tertiary alcohol? A) Ethanol B) 2-propanol C) 2-methyl-2-propanol D) 1-pentanol Correct answer: C Rationale: 2-methyl-2-propanol has the -OH group on a carbon bonded to three other carbons, making it a tertiary alcohol. What does a positive result in the potassium permanganate (KMnO₄) test indicate? A) Presence of aromatic rings B) Presence of saturated compounds C) Presence of unsaturated compounds D) Presence of phenols Correct answer: C Rationale: KMnO₄ reacts with carbon-carbon double bonds in unsaturated compounds, turning from purple to brown. What does a positive result in the bromine test indicate? A) Presence of a hydroxyl group B) Presence of a ketone C) Presence of an unsaturated compound D) Presence of an acid Correct answer: C Rationale: Unsaturated compounds like alkenes react with bromine, causing the red color to disappear. What does a positive test with iron(III) chloride indicate? A) Presence of alcohol B) Presence of phenol C) Presence of ketone D) Presence of aldehyde Correct answer: B Rationale: Phenols form colored complexes with Fe³⁺ ions, usually giving red, purple, or blue colors. Which of the following is the correct IUPAC name for formaldehyde? A) Ethanal B) Methanal C) Propanal D) Ethanol Correct answer: B Rationale: Formaldehyde is the common name for methanal, the simplest aldehyde with one carbon. Which of the following compounds is an aldehyde with three carbon atoms? A) Acetone B) Propanal C) Butanal D) Propanol Correct answer: B Rationale: Propanal (also called propionaldehyde) is an aldehyde with three carbon atoms, ending in -CHO