The compound CH3CH2COOH is
CH3CH2COOH has three carbons with a carboxyl group (-COOH), identifying it as propanoic acid (C3H6O2). Acetic acid (A) is CH3COOH (two carbons), propanal (B) is CH3CH2CHO (an aldehyde), and propanol (C) is CH3CH2CH2OH (an alcohol). Thus, D is correct.
Alkaline hydrolysis of naturally occurring fats and oils yields
Alkaline hydrolysis (saponification) of fats and oils with a base (e.g., NaOH) produces soap (fatty acid salts) and glycerol. Option A is incorrect as fats are consumed, C refers to food products, and D describes the starting triglycerides (esters).
Which statement is incorrect about the acids HBr, HNO3, H2CO3, and H2SO4?
HBr, HNO3, H2CO3, and H2SO4 have pH < 7 (A), turn blue litmus red (B), and neutralize alkalis (C). HBr, a non-oxidizing acid, does not effectively react with marble (CaCO3) to liberate CO2, unlike the others, making D incorrect.
If the cost of electricity to deposit 1 g of magnesium is N5.00, how much would it cost to deposit 10 g of aluminium? [Al=27, Mg=24, F=96500 C/mol]
Mg²⁺ requires 2 moles of electrons per 24 g (2 × 96500 C/g). Charge for 1 g Mg = (2 × 96500) / 24 = 8033.33 C. Al³⁺ requires 3 moles per 27 g. Charge for 10 g Al = (3 × 96500 × 10) / 27 = 107222.22 C. Cost = (107222.22 / 8033.33) × 5 ≈ N33.33 (C). A, B, and D are incorrect.
During electrolysis of CuSO4 solution using copper electrodes, 16000 coulombs deposits how much copper at the cathode? [Cu=63.5, F=96500 C/mol]
Cu²⁺ + 2e⁻ → Cu. 1 mole Cu (63.5 g) requires 2 × 96500 = 193000 C. For 16000 C, moles Cu = 16000 / 193000 ≈ 0.0829 mol. Mass = 0.0829 × 63.5 ≈ 5.27 g, closest to 5.30 g (A). B likely assumes doubled charge, which is incorrect.
Which represents a carboxylic acid?
Carboxylic acids have the -COOH group (RCOOH, C). RCOOR (A) is an ester, RCHO (B) is an aldehyde, and RCOR (D) is a ketone.
Which statement is incorrect about alkenes?
Alkenes are unsaturated hydrocarbons with at least one double bond (C), undergo addition with halogens (A), and include ethene (D). B is incorrect as alkenes are unsaturated, unlike alkanes. This replaces the original question where all options were correct.
Elements with atomic numbers ³R, ¹⁹U, ²⁴S, ²⁰T, ¹⁹Y. Which is not true?
R (³H, tritium) is a hydrogen isotope (A). U and Y (¹⁹K) are potassium isotopes (B). R, U, S (²⁴Cr), and T (²⁰Ca) are metals or metalloids (C). T (²⁰Ca) is a metal, not a noble gas (D), making D incorrect.
Nitrogen is best separated from a nitrogen-oxygen mixture by passing over
Heated magnesium forms Mg3N2 with nitrogen, removing it and leaving oxygen (B). Potassium hydroxide (A) absorbs CO2, phosphorus (C) reacts with oxygen, and calcium chloride (D) absorbs water.
Water is 'hard' if it
Hard water contains Ca²⁺/Mg²⁺ ions, forming insoluble scum with soap (C). A, B, and D do not define hardness.
Sodium hydroxide pellets are
NaOH pellets absorb moisture and dissolve, indicating deliquescence (A). Hygroscopic (B) substances absorb moisture without dissolving, efflorescent (C) lose water, and hydrated (D) implies bound water.
Which structural formula is different? A: CH3CH2CH2CH2OH, B: CH3OCH2CH2CH3, C: CH3CH(OH)CH2CH3, D: CH3COCH2CH3
A, B, and C are C4H10O isomers. D (CH3COCH2CH3) is a ketone (C4H8O), differing in molecular formula and functional group.
Alkanes have the general formula
Alkanes are saturated hydrocarbons with the formula CnH2n+2 (e.g., CH4). A is for alkenes, C for alkynes, and D is not standard.
A liquid hydrocarbon in a jar of chlorine exposed to sunlight consumes all chlorine via
Unsaturated hydrocarbons (e.g., alkenes) undergo addition with Cl2, consuming chlorine (B). Polymerization (A), substitution (C), and reduction (D) do not fit.
In esterification of ethanoic acid with ethanol, H2SO4 acts as
H2SO4 protonates the carboxylic acid, acting as a catalyst (C). It also dehydrates (A), but its primary role is catalytic.
A sea shell in dilute HCl produces a colourless, odourless gas turning lime water milky. The shell contains
CaCO3 in shells reacts with HCl to produce CO2, which turns lime water milky (B). A, C, and D do not produce CO2.
A metal salt gives a white precipitate with NaOH, soluble in excess NaOH, and a white precipitate with NH3, soluble in excess NH3. The cation is
Zn²⁺ forms Zn(OH)2, soluble in excess NaOH ([Zn(OH)4]²⁻) and NH3 ([Zn(NH3)4]²⁺). Ca²⁺ (B) and Pb²⁺ (D) form insoluble precipitates, and Al³⁺ (C) is insoluble in excess NH3.
The IUPAC name for CH3CH(CH3)CH2CH3 is
Longest chain: 4 carbons (butane), methyl on carbon 2: 2-methylbutane (A). C and D suggest a 5-carbon chain, and B misplaces the methyl.
At STP, how many litres of H2 are produced from 500 cm³ of 0.5 M H2SO4 with excess metal? [1 mol gas = 22.4 dm³]
Moles H2SO4 = 0.5 × 0.5 / 1000 = 0.25 mol. H2SO4 → H2 (1:1). Volume H2 = 0.25 × 22.4 = 5.6 dm³ (B).
Which element is in the p-block?
Chlorine (3s²3p⁵) is in the p-block. Sodium (A), Magnesium (B), and Calcium (D) are s-block.
Which substance conducts electricity?
Graphite’s delocalized electrons enable conductivity (B). Sulphur (A), diamond (C), and red phosphorus (D) are insulators.
An organic compound with 72% C, 12% H, 16% O has an empirical formula [C=12, H=1, O=16]
C = 72/12 = 6, H = 12/1 = 12, O = 16/16 = 1. Ratio: 6:12:1, simplified to 3:6:1, giving C3H6O (A).
0.499 g of CuSO4·xH2O gives 0.346 g residue on heating. The value of x is [Cu=63.5, S=32, O=16, H=1]
Water lost = 0.499 - 0.346 = 0.153 g. Moles CuSO4 = 0.346 / 159.5 ≈ 0.00217 mol. Moles H2O = 0.153 / 18 ≈ 0.0085 mol. x = 0.0085 / 0.00217 ≈ 5 (D).
Which suggests a solid sample is a mixture?
Mixtures melt over a range due to varying components (C). A, B, and D are not specific to mixtures.
Hydrogen diffuses through a porous plug compared to oxygen
Graham’s law: rate ∝ 1/√M. M(H2) = 2, M(O2) = 32. Rate H2 / Rate O2 = √(32/2) = 4. Hydrogen diffuses four times faster (C).
How many moles of Fe2O3 are in 1 kg? [Fe=56, O=16]
Molar mass Fe2O3 = (2 × 56) + (3 × 16) = 160 g/mol. Moles = 1000 / 160 = 6.25 mol (B).
3.0 g of K2CO3 and KCl mixture in 250 cm³ solution. 25 cm³ needs 40 cm³ of 0.1 M HCl. The percentage of K2CO3 is [K=39, C=12, O=16]
Moles HCl = 0.1 × 0.04 = 0.004 mol. K2CO3 + 2HCl → 2KCl + H2O + CO2. Moles K2CO3 = 0.004 / 2 = 0.002 mol. Total moles = 0.002 × 10 = 0.02 mol. Mass = 0.02 × 138 = 2.76 g. % = (2.76 / 3.0) × 100 ≈ 92% (D).
At 300 K, the solubility of KCl is 35 g/100 g water. How much KCl dissolves in 200 g water?
Solubility = 35 g/100 g water. For 200 g water, mass = 35 × 2 = 70 g (B).
If 80 g of KCl is added to 100 g water at 353 K, what happens? [Solubility at 353 K = 50 g/100 g water]
Solubility = 50 g/100 g water. 80 g added, 50 g dissolves, 30 g remains undissolved (B).
If KCl’s molar mass is 74.5 g, moles dissolved in 100 g water at 343 K (solubility 45 g/100 g) is
Solubility = 45 g. Moles = 45 / 74.5 ≈ 0.6 mol (A).
Which are not properties of alkalis?
Alkalis have slippery feel, pH > 7 (B), yield NH3 (C), and turn phenolphthalein pink (D). Sour taste and pH < 7 (A) are acidic properties.
A gas at 298 K has its volume and pressure quadrupled. The new temperature is
P1V1/T1 = P2V2/T2. P2 = 4P1, V2 = 4V1, T1 = 298 K. T2 = (4 × 4 × 298) / 1 = 1192 K (B).
Zn does not liberate H2 with HNO3 because
HNO3 oxidizes H2 to H2O, producing nitrogen oxides (B). Zn is not passive (A), C is a consequence, and HNO3 is strong (D).
Which has the highest vapour pressure at 323 K? Boiling points: water (373 K), ethanol (351.3 K), toluene (383.6 K), butan-2-ol (372.5 K)
Lowest boiling point (ethanol, 351.3 K) indicates highest vapour pressure at 323 K (B).
Two nitrogen samples: Sample 1 from air with CO2 and O2 removed, Sample 2 from N2O over heated Cu. Sample 1 is
Sample 1 contains inert gases (e.g., argon), making it less reactive than pure N2 (Sample 2, C).
Electrolysis of CuSO4 with Pt electrodes, 0.193 A for 2 hours, deposits how much Cu? [Cu=63.5, F=96500 C/mol]
Charge = 0.193 × 2 × 3600 = 1389.6 C. Moles Cu = 1389.6 / (2 × 96500) ≈ 0.0072 mol. Mass = 0.0072 × 63.5 ≈ 0.457 g (A).
For X + Y ⇌ Z, a catalyst
Catalysts increase the rate of both forward and reverse reactions without affecting equilibrium (B).
The formula of sodium gallate (Ga, +3 oxidation state) is
Ga³⁺ forms [GaO2]⁻ in alkaline solution, giving NaGaO2 with Na⁺ (A).
NO2 and Pb compounds in a city’s atmosphere come from
NO2 comes from automobile exhaust, Pb from leaded fuel or industrial emissions (D).
To increase yield in 2A(g) + B(g) ⇌ C(g) + 3D(g), ΔH = +X kJ, use
Endothermic reaction (+X kJ) favors products at higher temperature. Four moles of products vs. three moles of reactants favors lower pressure (A).
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