This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
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Here are the solutions to the questions: Question 6: Alkenes can be manufactured by The correct answer is C. Step 1: Analyze the options for manufacturing alkenes. A. Combustion of alkanes produces carbon dioxide and water. B. Polymerization reactions use alkenes as monomers to form polymers. C. Cracking of hydrocarbons* (larger alkanes) breaks them down into smaller alkanes and alkenes, which is a major industrial method for producing alkenes. D. Addition of hydrogen to unsaturated vegetable oils (hydrogenation) produces saturated fats (alkanes). Step 2: Identify the correct method. The cracking of hydrocarbons is a common industrial process used to produce alkenes. The final answer is C Question 8: Species that occur in a reaction pathway but not in the overall reaction are known as The correct answer is A. Step 1: Understand the definition of reaction species. Intermediates* are chemical species that are formed in one step of a reaction mechanism and consumed in a subsequent step. They do not appear in the overall balanced chemical equation. Reactants* are the starting materials that are consumed in the overall reaction. Inhibitors* slow down reactions but are not necessarily formed and consumed within the pathway. Products* are the substances formed at the end of the overall reaction. Step 2: Match the definition to the options. The description perfectly fits the definition of an intermediate. The final answer is A Question 9: Which of the following statements is correct? The correct answer is D. Step 1: Evaluate each statement. A. Pentane (C_5H_12) has 3 structural isomers: n-pentane, isopentane (2-methylbutane), and neopentane (2,2-dimethylpropane). So, the statement "Pentane has five isomers" is incorrect. B. Butane (C_4H_10) has a higher molecular weight than propane (C_3H_8). For alkanes, boiling points generally increase with increasing molecular weight due to stronger London dispersion forces. Therefore, butane has a higher* boiling point than propane. This statement is incorrect. C. Alkanes undergo substitution reactions* with halogens (like chlorine) in the presence of UV light, not addition reactions. Addition reactions are characteristic of unsaturated compounds like alkenes and alkynes. This statement is incorrect. D. The general formula for an alkane is C_nH_2n+2. For an alkane with 49 carbon atoms (n=49), the number of hydrogen atoms is 2(49) + 2 = 98 + 2 = 100. This statement is correct. The final answer is D Question 10: The best indicator to use for the titration of ethanoic acid with sodium hydroxide is The correct answer is B. Step 1: Identify the nature of the acid and base. Ethanoic acid (CH_3COOH) is a weak acid*. Sodium hydroxide (NaOH) is a strong base*. Step 2: Determine the pH at the equivalence point. The titration of a weak acid with a strong base results in an equivalence point that is in the basic region (pH > 7). Step 3: Select an indicator suitable for the equivalence point pH. Phenolphthalein* changes color in the pH range of approximately 8.2-10.0, which is suitable for a basic equivalence point. Methyl orange (pH 3.1-4.4), screened methyl orange (pH ~3.2-4.2), and methyl red* (pH 4.4-6.2) change color in the acidic range, making them unsuitable for this titration. The final answer is B Question 11: The reduction half equation of the following reaction is: Zn_(s) + CuSO_4(aq) ZnSO_4(aq) + Cu_(s) The correct answer is C. Step 1: Determine the oxidation states of the elements involved. In the reaction: Zinc (Zn) goes from an oxidation state of 0 in Zn_(s) to +2 in ZnSO_4(aq) (Zn^2+). This is oxidation* (loss of electrons). Copper (Cu) goes from an oxidation state of +2 in CuSO_4(aq) (Cu^2+) to 0 in Cu_(s). This is reduction* (gain of electrons). Step 2: Write the reduction half-equation. Reduction involves the gain of electrons. The copper ion Cu^2+ gains electrons to become neutral copper metal Cu_(s). To balance the charge, two electrons are needed. Cu^2+_(aq) + 2e^- Cu_(s) Step 3: Compare with the given options. Option C matches the derived reduction half-equation. Option A is a dissolution equation. Option B shows only one electron gained, which is incorrect for Cu^2+ to Cu. Option D is the oxidation half-equation for zinc. The final answer is C That's 2 down. 3 left today — send the next one.