Various options are provided as possible answers to the following questions - NSC Physical Sciences - Question 1 - 2024 - Paper 2
Question 1
Various options are provided as possible answers to the following questions. Each question has only one correct answer. Choose the answer and write only the letter (... show full transcript
Worked Solution & Example Answer:Various options are provided as possible answers to the following questions - NSC Physical Sciences - Question 1 - 2024 - Paper 2
Step 1
1.1 The functional group for an ALDEHYDE is …
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Answer
The correct answer is C. carbonyl group. Aldehydes are characterized by the presence of a carbonyl group (C=O) at the end of a carbon chain.
Step 2
1.2 Which ONE of the following equations represents the reaction for the IDENTIFICATION of an UNSATURATED compound in the laboratory?
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Answer
The correct answer is B. CH3CH2CH=CH2 + Br2 → CH3CH2CHBrCH2Br. This reaction represents the addition of bromine to an alkene, which is a common method for identifying unsaturated compounds.
Step 3
1.3 Which ONE of the following is the EMPIRICAL formula of ethyl ethanoate?
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Answer
The correct answer is A. C2H4O. The empirical formula represents the simplest whole-number ratio of the elements in the compound, and for ethyl ethanoate, that is C2H4O.
Step 4
1.4 In an experiment 5 g of calcium carbonate, CaCO3(s), reacts with EXCESS hydrochloric acid, HCl(aq), at a temperature of 40 °C. Which ONE of the curves will now be obtained?
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Answer
The correct answer is B. Curve II. Increasing the amount of CaCO3 will lead to a faster reaction rate, thus producing more CO2 and changing the graph accordingly.
Step 5
1.5 Which statement(s) is/are TRUE when a few drops of concentrated hydrochloric acid, HCl(conc), are added to the mixture?
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Answer
The correct answer is B. (i) and (ii) only. Adding a strong acid will favor the reverse reaction and increase the concentration of Cr2O7^2−.
Step 6
1.6 If the equilibrium constant Kc = 1 × 10^4, then …
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Answer
The correct answer is A. [A][B] < [C][D]. A large Kc indicates that the products are favored at equilibrium.
Step 7
1.7 Which ONE of the following shows the PRODUCTS for the reaction of oxalic acid with sodium hydroxide?
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Answer
The correct answer is A. (COO)2Na2(aq) + H2O(l) + CO2(g). This represents the neutralization reaction between oxalic acid and sodium hydroxide.
Step 8
1.8 Which ONE of the following Ka values represents the WEAKEST acid at 25 °C?
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Answer
The correct answer is C. 1.8 × 10^2. The higher the Ka value, the stronger the acid, thus this represents the weakest acid.
Step 9
1.9 Which ONE of the following combinations is CORRECT for the changes occurring at the anode, cathode and in the electrolyte when the cell is in operation?
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Answer
The correct answer is D. Decreases, Increases, No change. During electrolysis, the anode mass decreases, cathode mass increases, and the color of the electrolyte remains unchanged.
Step 10
1.10 Which ONE of the following redox reactions is SPONTANEOUS under standard conditions?
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Answer
The correct answer is D. Cu + Pb2+ → Cu2+ + Pb. This reaction is spontaneous since it represents a favorable transfer of electrons.
